*[http://www.biodiversitylibrary.org/search.aspx?SearchTerm=Piper%20nigrum&SearchCat= BHL]
*[http://ecocrop.fao.org/ecocrop/srv/en/cropView?id=1714 FAO Ecocrop]
*[http://gernot-katzers-spice-pages.com/germ/Pipe_nig.html Gernot Katzer's Spice pages]
*[http://www.botanical.com/botanical/mgmh/comindx.html Grieve's herbal]
*[http://www.ars-grin.gov/cgi-bin/npgs/html/tax_search.pl?Piper%20nigrum GRIN]