3 links
Growing Hydroponic Tomatoes
ag.arizona.edu
Interactive web site from the University of Arizona provides practical, accurate information on growing hydroponic tomatoes for students, hobbyists, and beginning growers.
Hydroponics as a Hobby
ag.uiuc.edu
A circular from the Extension at University of Illinois at Urbana-Champaign, offers a basic history and guide to hobby hydroponics.
Role of Perlite in Hydroponic Culture
schundler.com
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