books.google.co.uk - Need-to-know information on the classification and identification of aquatic invertebratesThis Fourth Edition of the standard reference used by generations of professionals and students is the source for authoritative information on the natural history, ecology, and taxonomy of free-living American freshwater...http://books.google.co.uk/books/about/Pennak_s_Freshwater_Invertebrates_of_the.html?id=GqIctb8IqPoC&utm_source=gb-gplus-sharePennak's Freshwater Invertebrates of the United States
