Hydroponic Society of America  
   Non-profit organization dedicated to the exchange of information in the field of hydroponics. Members include educators, researchers, vendors, commercial growers and hobbyists.
   http://hsa.hydroponics.org

Hydroponics Resource for Inexpensive Startups  
   Secrets for starting hydroponic businesses. Includes information about hydroponic nutrients, maintenance, production, greenhouses, and marketing.
   http://www.mayhillpress.com

Institute for Simplified Hydroponics  
   Dedicated to supporting efforts to use simplified hydroponics to reduce global hunger and poverty. Offers classes and activities to support the education of simplified hydroponics, especially in developing nations.
   http://www.carbon.org

Role of Perlite in Hydroponic Culture  
   A research report issued by the Perlite Institute, Inc. by Dr. David A. Hall, Principal of the Pershore College of Horiculture in the United Kingdom
   http://www.perlite.org/guides/pg09.htm

History of Hydroponics  
   Gary V. Deutschmann covers the history and future of hydroponic gardening.
   http://archimedes.galilei.com/raiar/histhydr.html

Growing Hydroponic Tomatoes  
   Interactive web site from the University of Arizona provides practical, accurate information on growing hydroponic tomatoes for students, hobbyists, and beginning growers.
   http://www.ag.arizona.edu/hydroponictomatoes/

The Growing Edge  
   A bimonthly magazine dedicated to hydroponics, aquaponics, and greenhouse growing. Provides a wealth of free information for soilless growers.
   http://www.growingedge.com

How To Produce Green Fodder Hydroponically  
   Book on small scale cultivation of green fodder via the hydroponic method. Website in Spanish and English.
   http://orbita.starmedia.com/~carlosarano

Home Hydroponics  
   An excellent introduction to the hydroponic methodology from the Virginia Cooperative Extension.
   http://www.ext.vt.edu/pubs/envirohort/426-084/426-084.html

Hydroponic Gardening - Suite101.com  
   The Hydroponic Gardening page at Suite101.com, a community site. Offers articles, links and discussions pertaining to hydroponics.
   http://www.suite101.com/welcome.cfm/hydroponic_gardening

Hydroponics as a Hobby  
   A circular from the Extension at University of Illinois at Urbana-Champaign, offers a basic history and guide to hobby hydroponics.
   http://www.ag.uiuc.edu/~vista/html_pubs/hydro/hydrotoc.html

Crop Physiology Laboratory - Hydroponics  
   Excellent source of information for recirculating hydroponics methodology from Utah State University.
   http://www.usu.edu/cpl/research_hydroponics.htm

Hydroponics Project  
   Photographic presentation of hydroponics project at Colorado State University.
   http://www.angelfire.com/pa3/padraig/

Hydroponic Lettuce Production  
   Details of setting up and running a lettuce production facility using Controlled Environment Agriculture techniques. Illustrated with descriptive photos. Cornell University.
   http://www.bee.cornell.edu/extension/CEA/Lettuce_Handbook/introduction.htm