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

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

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

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

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

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