Cannabis sativa
   Information on Hemp, its physical characteristics, uses and cultivation.
   http://www.ibiblio.org/pfaf/cgi-bin/arr_html?Cannabis+sativa&CAN=LATIND

Cannabis sativa L.
   Image from Botanical Department - University of Catania.
   http://www.dipbot.unict.it/orto/1037-1.html

Ethnobotanical Leaflets - Cannabis: The Hemp Plant
   A publication of Southern Illinois University Herbarium by Ernest G. Walker, Jr. on Cannabis sativa, Cannabis indica, and Cannabis ruderalis. With references.
   http://www.siu.edu/~ebl/leaflets/hemp.htm

Flora of North America - Cannabis sativa Linnaeus
   Harvard University Flora Online. Includes description, line drawings, and U.S. distribution map.
   http://flora.huh.harvard.edu:8080/flora/browse.do?flora_id=1&taxon_id=200006342

Hemp: A New Crop with New Uses for North America
   By Ernest Small and David Marcus. Reprinted from: Trends in new crops and new uses. 2002. p. 284–326. J. Janick and A. Whipkey (eds.). ASHS Press, Alexandria, VA. One of the best documents about Cannabis on the Web. (PDF file 14.1MB)
   http://www.hort.purdue.edu/newcrop/ncnu02/pdf/small.pdf

Plant Profile for Cannabis sativa
   Information from the USDA Plants database.
   http://plants.usda.gov/java/profile?symbol=CASA3

Wisconsin Vascular Plants: Species Details
   Cannabis sativa L. hemp, Indian hemp.
   http://www.botany.wisc.edu/wisflora/scripts/detail.asp?SpCode=CANSAT