EDAS Plant Study Group Canberra Aquatic Plant Group DFW Aquatic Plant Club The Crypts Pages Aquatic Gardeners Association Steve's Aquatic Plant Resource Page Tropica Aquarium Plants Aqua Botanic's True Aquarium Plants Aquarium Plant's Mailing List Greater Washington Aquatic Plant Association (GWAPA) Chicago Aquatic Gardeners Association (CAGA) Aqua Design Amano The Nature Aquarium San Francisco Bay Area Aquatic Plant Society (SFBAAPS) Chuck Gadd's excellent dosage calculator Tom Barr's "Estimative Index" method Tom Barr's "Estimative Index" method (HTML version) All Wet Thumb Forums Aquatic Plant Central