Raphia P. (PROSEA)

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Plant Resources of South-East Asia
Introduction
List of species


Raphia P. Beauv.


Protologue: Fl. Oware 1: 75, t. 44-46 (1806).
Family: Palmae (Arecaceae)
Chromosome number: n= 14, 16;R. farinifera: 2n= 32;R. hookeri,R. vinifera: 2n= 28

Major species and synonyms

  • Raphia farinifera (Gaertn.) Hylander, Lustgårten 31-32: 88 (1952), synonyms: R. pedunculata P. Beauv. (1806), R. ruffia (Jacq.) Mart. (1838), R. kirkii Engl. ex Becc. (1910).
  • Raphia hookeri G. Mann & H. Wendl., Trans. Linn. Soc. 24: 438 (1864), synonyms: R. gigantea A. Chev. (1932), R. sassandrensis A. Chev. (1932).
  • Raphia vinifera P. Beauv., Fl. Oware 1: 77 (1806), synonym: R. diasticha Burret (1942).

Vernacular names

  • General: raphia palm (En). Raphia (Fr).
  • R. farinifera : Madagascar raphia palm, Bamenda raphia (En).
  • R. hookeri : wine palm, Ivory Coast raphia palm, giant raphia palm (En).
  • R. vinifera : bamboo palm, king bamboo palm (En). Palmier bambou (Fr).

Origin and geographic distribution

Raphia comprises about 28 species, mostly African ones, with 1 species ( R. taedigera Mart.) occurring in tropical America. R. farinifera is distributed throughout Central and East Africa and in Madagascar, where it is probably introduced, and has naturalized in the Lesser Antilles. In Africa it is also cultivated (Nigeria, Madagascar) and semi-cultivated. Outside Africa it is grown in India, Singapore and (rarely) in Java. R. hookeri is found from Gambia through the forest zone of West Africa to Cameroon, Gabon and Congo and possibly to Angola. It is occasionally cultivated or semi-cultivated. Outside Africa it is grown in India, Peninsular Malaysia and Singapore. R. vinifera occurs from Benin to Congo. It is grown in Nigeria, Cameroon, India and Singapore and possibly in Java.

Uses

No information is available on the extent to which raphia palms are presently used in South-East Asia, but elsewhere they have a wide range of applications, which could be potentially considered for South-East Asia. Two valuable types of fibre are obtained from raphia palms: "raffia" and "piassava" (or "bass"). The soft but strong raffia fibre is obtained by pulling off ribbon-like strips from the upper surface of the leaflets of young, unfolding leaves of R. farinifera , R. hookeri and R. vinifera . Raffia fibre is used in Africa to make articles such as mats, hats, baskets, bags, ropes, belts, hammocks, curtains and ceremonial costumes. It may also be woven into cloth. In Europe it is used as tying material in horticulture and for handicrafts. The strong piassava fibre ("African piassava" or "African bass") is obtained from the vascular bundles of the petiole and leaf sheath, mainly from R. hookeri . It is used locally in Africa to make weather-resistant coarse ropes, belts for climbing oil palms, brushes, fish-traps, hats, baskets and screens. In Europe it serves for the production of brooms and brushes. Piassava fibre can be processed into exceptionally strong paper and other stem and leaf fibres are also considered potential sources of pulp and paper.

Raphia leaves, often split lengthwise, are used for thatching in Africa. They are also made into mats, baskets and other articles of wickerwork, and hut-walls and fences. Split midribs of R. vinifera are woven into floor-mats. The midribs and petioles of Raphia leaves ("raffia bamboo" or "bamboo") are used for poles, rafters, ladders, furniture and cross-bearers in canoes. Split lengthwise they are made into screens. The trunks are applied in house construction.

Sap tapped from the stems of R. farinifera and R. hookeri ferments rapidly into palm wine. R. vinifera is not much used for this purpose, because its taste is not appreciated. The wine is distilled into a strong alcoholic liquor and can also be used as bakers' yeast. Oil is extracted from the boiled mesocarp pulp and the kernels of various raphia palms and utilized for food ("raphia butter") and non-food purposes (soap, stearin, fuel, lubricant, pomade). Raphia fruits are eaten boiled, and seeds are consumed boiled or roasted. The raw fruit of R. hookeri is poisonous and in crushed form it is used as fish-poison. The mesocarp of the fruit of R. hookeri is used in traditional medicine for its laxative and stomachic properties and as a liniment for pains. The terminal bud of all raphia palms is eaten as palm cabbage. Raphia wax is obtained from the lower surface of the leaves and serves as polish for floors and boats and for making candles.

Production and international trade

Most of the raffia entering the international market is produced in Madagascar from R. farinifera . The main importing countries are the United States, France, Germany, Hong Kong and the United Kingdom. Recent production and trade statistics are not available. The main piassava-yielding raphia palm is R. hookeri . Its piassava has been exported from West Africa to temperate countries (mainly Europe) for the production of brooms and brushes since the end of the 19th Century, when the supply of South-American piassava from Attalea funifera Mart. ("Bahia piassava" or "Bahia bass") and Leopoldinia piassaba Wallace ("Para piassava" or "Monkey bass"), used in Europe for brooms since the middle of the 19th Century, could no longer meet demand. The trade reached its peak in the 1950s and 1960s, after which it declined following the advent of plastic brooms. The quality of African piassava for broom-making is such that it still enters the international market. The main types of African piassava fibre in trade are "Sherbro", "Sulima" and "Calabar". Sherbro and Sulima are obtained from the petiole, the former from R. hookeri and the latter from R. palma-pinus (Gaertn.) Hutch. (synonyms: R. gaertneri Becc., R. gracilis Becc.), often with an admixture of R. hookeri fibres, whereas Calabar is extracted from the leaf sheath of R. hookeri . The leaf sheaths of R. palma-pinus are rather short and do not yield high-quality fibre.

Properties

Raffia fibre is well suited to horticultural purposes, because it is supple and durable and it does not have sharp edges which might damage tender plant parts. It is easily dyed, making it suitable for the production of fancy articles. R. hookeri yields high-quality raffia with a high tenacity. This is due to the hypodermic layer of the leaflets of R. hookeri consisting of thick fibres which are arranged in a continuous ribbon-like layer. In R. vinifera and R. sudanica A. Chev. the fibres are not arranged in a ribbon-like layer, but discontinuously, which accounts for the lesser tenacity of their raffia fibre.

Piassava fibre is water resistant, hard-wearing, and has the right balance between stiffness and elasticity to give a firm stroke to a broom and sufficient spring action to make the broom self-cleaning. The best piassava fibre is cylindrical with a firm wall and soft core and a diameter of 1-1.5 mm. It is obtained from the sides ("wings") of the petiole, whereas fibre from the upper and lower surface is of only reasonable quality. Fibres near the central flattened ridge are woody and brittle. The central core of the petiole gives a soft fibre ("straw" or "piassava tow") which may be used as adulterant or as a substitute for coir. The best quality Calabar fibre is obtained from the sides of the leaf sheath, i.e. not near the suture and not near the midrib. Fibre obtained from the midrib of the leaf sheath is softer and more pliable making it suitable for plaiting ropes. Calabar piassava is stiffer than Sherbro and Sulima and tends to be black, whereas Sherbro and Sulima are pale at harvest, but turn darker during retting. Mature leaves yield higher quality piassava fibre than young leaves.

Both the stem and petiole of R. hookeri are suitable as raw material for the paper industry. Stem fibres are mostly thick walled and on average 2.4 mm long and (17-)30(-46) μm wide. The fibres of the petioles are on average 1.7 mm long and (10-)18(-27 μm) wide. Many fibres have scalloped walls. The pitted vessel elements of the stem are few in number but very large, up to 5 mm long and 350 μm wide, whereas those of the petioles are generally smaller. Pulp from R. hookeri also contains rounded, thick-walled parenchyma cells and spherical silica bodies. Dry stems contain about 74% fibre, 25% parenchyma, and 1% vessel elements.

Palm wine obtained from R. hookeri is attractively milky-white in colour, but is weaker and less popular than that from oil palm ( Elaeis guineensis Jacq.). The fresh sap tastes like ginger beer. The alcohol content of the palm wine increases from less than 2% to about 5% during the first 8 days of tapping, remaining constant thereafter.

The major fatty acids in mesocarp oil and seed oil of raphia palms are palmitic acid, oleic acid and linoleic acid. Raphia oil resembles that of oil palm in colour, taste, odour and chemical composition, except that it contains more linoleic acid, giving it a higher unsaturated acid content. The raw fruit of R. hookeri contains toxic and antinutritional factors, such as hydrocyanic acid, tannins, oxalates and phytic acid, but cooking reduces the level of these. In bioassays the aqueous and butanol fractions of the methanolic extract of R. hookeri mesocarp showed cytotoxicity against brine shrimp, and the butanol fraction also against mosquito larvae and 5-day old tadpoles.

Adulterations and substitutes

In South-East Asia Corypha utan Lamk plays a role very similar to that of Raphia in Africa, yielding various types of fibres (including petiole fibre and a kind of raffia fibre from the leaflets), thatch and palm wine. Other palms, such as Borassus flabellifer L. and Nypa fruticans Wurmb, also yield material for weaving, thatch and palm wine in South-East Asia. In the market of raw material for brooms and brushes, Raphia competes with Attalea funifera and Leopoldinia piassaba and with synthetic material.

Description

Solitary or clustered, armed, monoecious, acaulescent or erect palms. Stem subterranean to erect, massive, internodes short and often with spine-like roots, usually partly obscured by the long persistent leaf bases. Leaves large, sheathing, reduplicately pinnate, withering before being shed; sheath unarmed, splitting opposite the petiole, with or without a conspicuous ligule, disintegrating into thin sheets or sometimes partly into black fibres that clothe the stem; petiole short to very long, unarmed, usually deeply channelled adaxially only at the base, rounded distally; rachis unarmed, angled adaxially, rounded abaxially; leaflets numerous, linear, single fold, regularly arranged or grouped and fanned within the groups to give the leaf a plumose appearance, often whitish-waxy beneath, armed with short spines along the margins and the midrib. Inflorescence produced simultaneously in the axils of the most distal few leaves, either interfoliar and pendulous, or aggregated into a massive, erect, suprafoliar, compound inflorescence; peduncle short; first bract (prophyll) tubular, 2-keeled, closely sheathing to inflated; peduncular bracts several, about 6, inflated basally with triangular limbs; rachis much longer than the peduncle, repeatedly branched, each first order branch with faintly 4-ranked bracts each with an axillary rachilla; rachilla with distichous, tubular bracts each one subtending a unisexual flower, upper part of the rachilla bearing male flowers, basal part bearing female flowers; male flower with tubular 3-lobed calyx, a tubular corolla with 3 free petal lobes, stamens 6-20 or more, usually partly connate by the fleshy filaments, small pistillode sometimes present; female flower with calyx and corolla as in male one, usually a staminodial ring with sterile anthers, a pistil with 3 free or connate terminal stigmas, a 3-loculed-ovary covered with vertical rows of reflexed fimbriate scales. Fruit usually a 1-seeded drupe or berry, tipped with the stigmatic remains and covered with the enlarged scales arranged in vertical rows, each normally with a depressed vertical central line; mesocarp thick, oily; wall of endocarp spongy. Seed with a thick, dry testa and endosperm penetrated by rather large ruminations. Germination adjacent-ligular; seedling leaf pinnate.

  • R. farinifera . A clustering palm, up to 25 m tall with stout trunk up to 10 m tall and 1 m in diameter, covered with persistent leaf sheaths. Leaves erect, about 12 in the crown, slightly spreading, up to 20 m long; petiole rounded in cross-section, sheath and petiole about 1.5 m long; rachis stout, several m long, reddish; leaflets up to 150 on each side of the rachis, inserted in 2 planes, stiff, linear, the median about 1 m × 3-8 cm, basal and terminal ones smaller, white-waxy at underside, margins and upperside midrib with yellowish spines. Inflorescence pendulous, up to 3 m × 35 cm, branched to 2 orders; primary inflorescence bract about 30 cm × 20 cm, tubular, partially enclosing the first and second order branches; peduncular bract 18 cm × 8 cm, tubular for 11 cm; second order prophylls 9 cm long; first order branches with 13-32 rachillae; rachilla 6-13 cm × 5-8 mm; male flowers: calyx tube 4.5-5 mm tall, lobes very small, corolla tube 2-3 mm long, lobes narrowly ovate, 6-6.6 mm × 2-2.5 mm, stamens 6, inserted at the mouth of the tube, filaments slightly connate, 2-3 mm long, pistillode absent; female flowers: calyx 5-6.5 mm tall, corolla tube 1-1.3 mm long, lobes narrowly triangular, about 3 mm × 1.5 mm, staminodes absent, ovary 5.5 mm × 2.7 mm. Fruit very variable at maturity, ovoid to ellipsoid, 5-10 cm × 4-5.5 cm, base conical, apex rounded and with a beak 5 mm long, scales in 12-13 rows, largest scales 15 mm × 18 mm, brown. Seed ovoid to ellipsoid, 3-6 cm × 3-4 cm, endosperm sparsely to densely ruminate.
  • R. hookeri . A palm with trunk up to 10 m tall and 30 cm in diameter, usually single, not forming a clump, but occasionally with 1-4 suckers; upper part of the trunk clad with blackish fibres (persistent withered leaf-bases). Leaves arranged spirally, pinnate, up to 12 m long, erect, dark green and shining above, waxy and glaucous below; sheath 3-4 m long; petiole 3-4 m long; leaflets 1-1.5 m × 4-5 cm, about 200 on each side of the rachis, terminal segments gradually narrowing to a fine point and having spines on the upper side of the midrib and on margins. Inflorescence axillary, pendulous, 2.5 m or more long, branched to 2 orders, compressed-cylindrical, with crowded branches; branches bearing many curved ultimate branchlets in 4 rows but mostly compressed into a plane; branchlets 15-23 cm long, rigid; branches and branchlets with short-tubular, truncate bracts at base; flowers unisexual; male flowers 1.5-2.5 cm long, with 1 bracteole slightly longer than calyx, thick, with blunt lobes, corolla much longer than calyx, curved, with segments thickened near the tip, stamens (15-)18-22(-24), with erect, linear anthers; female flowers larger than male ones, with 2 bracteoles, calyx as in male flowers, corolla about as long as calyx, with acuminate segments thickened near tip, staminodes 12-15, ovary superior, 3-celled, stigma sessile, recurved, subulate. Fruit a 1-seeded berry, inversely conical or ellipsoid, 6-12 cm × 4-5 cm, with stout beak 1-1.5 cm long, more or less obliquely tipped, covered with scales in (11-)12(-15) vertical rows; scales convex, slightly less broad than long, narrowly furrowed, reddish-brown or pale yellowish-brown with darker point, obtuse at the base, almost entire. Seed cylindrical, 6-7.5 cm × 3-3.5 cm, irregularly grooved; albumen narrowly ruminate. Seedling with hypogeal germination.
  • R. vinifera . A palm with stout trunk up to 5 m long and a crown of arching leaves up to 13 m long. Leaves bright green, shining above, rather glaucous and waxy below; rachis stout, light brown to orange; terminal leaflets linear with spiny margins and a ragged or blunt tip; mid-veins spiny above with fine brown spines at intervals of 1-2 cm. Inflorescence pendulous; partial inflorescences (branches) 30-60 cm long; bracts of peduncle and branch-bases ring-like, short; rachillae in 4 ranks, 10-15 cm long, slender, curved, laterally compressed, tapering; male flowers curved, 8 mm long, bracteole sharply bicarinate behind, encloses the calyx, calyx almost cup-shaped, roundly 3-lobed, chaffy at the margin, corolla nearly 3 times the length of calyx, splits into 3 segments almost to the base, stamens usually (6-)9, filaments thick, completely free or connate for half their length; female flowers with outer bracteole slightly longer than calyx, calyx cup-shaped, tridentate, corolla one-third longer than calyx, divided halfway into 3 pointed segments, staminodial ring fused to the corolla with 9 deltoid sterile anthers. Fruit cylindrical-ellipsoid, 6.5-9 cm × 3.5-4 cm wide, ending abruptly in a small sharp beak 3-5 mm long; scales in 9 rows, rhomboid, about 2 cm × 2 cm, rather flat or slightly concave towards the point of the scale, brown. Seed ovoid to ellipsoid, slightly narrower at one end than the other; endosperm deeply ruminate.

Growth and development

Raphia is monocarpic: the palms flower and fruit only once, followed by death. Inflorescences are produced more or less simultaneously in the axils of the most distal leaves. Tapping for wine may damage the developing inflorescence, making flowering impossible and accelerating death. Germination of R. hookeri seeds requires 20-40 days. When young its main stem forms a few suckers. The time from planting to flowering in R. hookeri is 3-7 years, whereas R. vinifera requires about 8 years. R. hookeri is protogynous and cross-pollinated, mainly by wind. The fruits reach maturity at 1-4 years after the onset of flowering and the palm dies 3-4 years after fruit fall. R. farinifera in Madagascar takes about 20-25 years from seed to flowering and 5-6 years from flowering to ripe fruit, with all fruits maturing in the same year.

Other botanical information

Raphia is an isolated genus, comprising approximately 28 species, with no obvious close relatives. It is classified within the Palmae in the subfamily Calamoideae , tribe Calameae , subtribe Raphiinae . Raphia is mostly described as having several inflorescences in the axils of the topmost leaves. Alternatively it is sometimes described as forming one massive terminal raceme branched from the base. Raphia leaves may be as long as 25 m and are the largest known among flowering plants. In most Raphia spp. several varieties and forms have been distinguished on the basis of local differences, but these subclassifications are without much practical value.

Ecology

Most raphia palms occur in swampy parts of lowland forest, where they may form dense, almost pure stands. In its natural distribution area R. farinifera is widespread in gallery forest and freshwater swamp-forest up to 2500 m altitude. It is common near villages at the edge of water courses. R. hookeri occurs in freshwater swamps and on river banks. It generally does not tolerate saline conditions and is said to prefer less wet conditions than R. vinifera . R. vinifera is also found in moist locations, especially on the edges of creeks.

Propagation and planting

Raphia palms are generally propagated by seed. Seedlings may be collected from the wild and raised in a nursery before being planted out in the field. It has been claimed that R. hookeri seeds should be sown with the ventral side upwards, because the embryo is located on this side, but experiments have shown that seed orientation does not influence germination or seedling growth. In Africa managed stands of R. hookeri are mostly left to rejuvenate naturally by seed and in Nigeria and Benin selected trees are left untapped for this purpose. R. vinifera is also propagated by suckers. Propagation by tissue culture techniques may offer potential for Raphia .

Husbandry

In West and Central Africa R. hookeri is exploited from natural stands, but it is also planted and tended on upland farms. Suckers are often removed by farmers to promote growth of the main stem. In some regions human activity (cutting of dicotyledonous trees, planting of R. hookeri ) has turned natural swamp vegetation into "rafiales", in which R. hookeri is the dominant species.

Diseases and pests

Fruit rot, caused by Thielaviopsis paradoxa (synonym: Chalara paradoxa ) affects R. hookeri and R. vinifera in Nigeria, causing dark brown rot of the mesocarp. It enters the fruit via wounds, sometimes killing the embryo and leading to loss of planting material. R. hookeri in Nigeria is affected by seedling blight, caused by Glomerella cingulata . Symptoms are transparent yellow circular spots appearing on the youngest fully expanded leaves, later becoming necrotic and coalescing. The infection spreads from the tip to the base of the leaflet and may lead to leaflet shedding. Severely infected seedlings may die. The aphid Cerataphis palmae may cause considerable damage to R. hookeri and R. vinifera , e.g. in Nigeria. No information is available on diseases and pests affecting raphia palms in South-East Asia.

Harvesting

Because palm wine from R. hookeri is highly prized, African farmers are reluctant to diminish plant vigour by cutting green leaves from this palm to obtain piassava fibre. However, dying leaves can be harvested with little effect on wine yields. As it is easier to remove the leaf sheaths from a fallen trunk, palms are often felled after tapping to harvest the fibre.

Tapping of R. hookeri for palm wine starts when the first small leaf (2-3 m) subtending an inflorescence appears. A cavity is cut in the stem just below the growing point and the resulting sap is collected. Raphia can usually be tapped for 18-25 days before the tree dies. Unlike oil palm, Raphia palms are seldom felled before tapping. For maximum oil yields, the fruits should be harvested 36-42 months after pollination.

Yield

No statistics on fibre yields of raphia palms are available. Palm wine yields of 870 l have been recorded from a single tree in a 2-month period from cutting to death, but average yields are about 100 l per palm.

Handling after harvest

To obtain raffia fibre, the young leaflets are detached and while still fresh a small incision is made on their lower side, near the top. The raffia fibre is then quickly pulled away by hand or by running the leaflet across a knife. The strips, about 1-2 m long and 2-3 cm wide, are tied together at one end and dried in the sun. On drying they develop a creamy yellow colour. Sometimes they are split into fine strands.

Piassava fibre extraction is different for leaf sheaths than for petioles, as the tissue of older leaf sheaths is already moribund and has started to soften. The outer thicker and more brittle fibres can be stripped off the leaf sheaths or are removed by burning the trunk. Starting from the outer "wings", the useful fibres are then sequentially stripped by hand. When fibre removal is difficult, usually in younger leaf sheaths, the tissue is beaten with a stick or the trunk is left exposed until the tissue has softened. The traditional practice of fibre extraction from the petiole, with its more solid tissue and hard epidermis, is to split the petiole along the longitudinal axis into 3 or 4 parts, which are then tied into bundles and retted in water. The retting period varies from a few weeks to 2-3 months. Retting influences the appearance of the fibres. Sherbro and Sulima piassava, somewhat pale at harvest, turn brownish during retting. Material retted in fresh running water tends to be pale brown, whereas that in stagnant swamp pools develops a reddish-brown tinge, which is more attractive and leads to higher prices. The extracted fibres still have a coating of decomposing background tissue which has to be removed, as the cleanliness of the fibre has a large impact on quality and market value. Cleaned fibres are dried in the sun for a few days. Further drying may occur under the eaves of houses or above fireplaces. High quality Sherbro and Sulima fibres show little variation in length, being about 1.5 m long. Though shorter fibres are acceptable, they should not be shorter than 25-30 cm. Calabar fibres are more variable in length and require sorting into bundles of uniform length.

Genetic resources and breeding

No germplasm collections or breeding programmes of Raphia are known.

Prospects

R. farinifera , R. hookeri and R. vinifera have been grown in South-East Asia since the 19th Century, but their importance has remained limited, notwithstanding their potential multiple use as a source of fibre, palm wine, thatch, construction material and oil for local use, and of raffia and piassava fibre for export. It is unlikely that the importance of raphia palms in South-East Asia will increase much, either for local use or for export: other palms fulfil the local roles that raphia palms have in Africa, whereas the global markets for raffia and piassava fibre are small and already saturated by production from African countries.

Literature

  • Brink, M., 2002. Raphia hookeri G. Mann & H. Wendl. In: Oyen, L.P.A. & Lemmens, R.H.M.J. (Editors): Plant Resources of Tropical Africa. Precursor. PROTA Programme, Wageningen, the Netherlands. pp. 120-125.
  • Burkill, H.M., 1997. The useful plants of West Tropical Africa. 2nd Edition. Vol. 4, Families M-R. Royal Botanic Gardens, Kew, United Kingdom. pp. 385-388.
  • Dransfield, J., 1986. Palmae. In: Polhill, R.M. (Editor): Flora of Tropical East Africa. A.A. Balkema, Rotterdam, the Netherlands. pp. 37-41.
  • Dransfield, J. & Beentje, H., 1995. The palms of Madagascar. Royal Botanic Gardens, Kew, United Kingdom & The International Palm Society, Lawrence, Kansas, United States. pp. 67-69.
  • Edem, D.O., Eka, O.U. & Ifon, E.T., 1984. Chemical evaluation of the nutritive value of the Raffia palm fruit (Raphia hookeri). Food Chemistry 15(1): 9-17.
  • Otedoh, M.O., 1973. The production of piassava in Nigeria. Nigerian Agricultural Journal 10(2): 260-264.
  • Profizi, J.-P., 1985. Raphia hookeri: a survey of some aspects of the growth of a useful swamp Lepidocaryoid palm in Benin (West Africa). Principes 29(3): 108-114.
  • Russell, T.A., 1965. The Raphia palms of West Africa. Kew Bulletin 19(2): 173-196.
  • Russell, T.A., 1968. Palmae. In: Hutchinson, J., Dalziel, J.M. & Hepper, F. (Editors), 1954-1972. Flora of West Tropical Africa. 2nd Edition. Vol. 3, part 1. Crown Agents for Oversea Governments and Administrations, London, United Kingdom. pp. 159-169.
  • Tuley, P., 1994. African bass/piassava - a historical perspective. Principes 38(1): 36-46.

Authors

H. Rustiami & M. Brink