Allium cepa (Onion)
   Plants for a Future: description, botanic details, cultivation, uses, range.
   http://www.pfaf.org/database/plants.php?Allium+cepa

Allium cepa proliferum (Tree Onion)
   Description, botanic details, cultivation, uses, and range.
   http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Allium+cepa+proliferum

Gernot Katzer's Spice Dictionary: Onions
   Onion's main constituents, origin, ethymology, and how it is used for cooking around the world.
   http://www.uni-graz.at/~katzer/engl/Alli_cep.html

Green Onions
   Guide for producing commercial green onions. University of Georgia.
   http://pubs.caes.uga.edu/caespubs/pubcd/C821.htm

History and Origin of the Onion
   Describes the origins of the Vidalia onion in Toombs County, Georgia and provides a history of onions from ancient Egypt to modern times.
   http://www.vidaliaonions.com/history.htm

Onion and Garlic Research at the University of Liverpool
   Research into flavor of Alliums using biochemical and molecular genetic methods, led by Dr. Hamish A. Collin and Dr. Meriel G. Jones.
   http://www.liv.ac.uk/~sd21/onion/onion_title.htm

Onion and Its Relatives
   Articles about cultivated onions from Purdue University.
   http://www.hort.purdue.edu/rhodcv/hort410/onions/onions.htm

Onions and Related Species
   Cultivating onions: fertility, planting, pest control, storage, varieties.
   http://www.ext.colostate.edu/pubs/garden/07614.html