en, G.J.H.; Denton, O.A. (2004) Plant Resources of Tropical Africa 2. Vegetables. PROTA Foundation, Wageningen; Backhuys, Leiden; CTA, Wageningen.↑ Zohary, Daniel; Hopf, Maria (2000). Domestication of plants in the Old World (Third ed.). Oxford: Oxford University Press. p. 198. ISBN 0-19-850357-1.↑ 13.0 13.1 13.2 Fritsch, R.M. (2002). "Chapter 1: Evolution, Domestication, and Taxonomy". In H.D. Rabinowitch and L. Currah (ed.). Allium Crop Science: Recent Advances. Wallingford, UK: CABI Publishing. pp. 20–21. ISBN 0-85199-510-1. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)↑ 14.0 14.1 14.2 14.3 14.4 Brickell, Christopher (ed) (1992). The Royal Horticultural Society Encyclopedia of Gardening. Dorling Kindersley. p. 345. ISBN 9780863189791. {{cite book}}: |first= has generic name (help)↑ 15.0 15.1 "Onions: Allium cepa". selfsufficientish.com. සම්ප්‍රවේශය 2006-04-02.↑ 16.0 16.1 16.2 16.3 16.4 16.5 "About Onions: History". සම්ප්‍රවේශය 2013-09-13.