Laboratory manuals 180 Annual report 158 Manuals 93 Handbooks, manuals, etc 83 Aquatic ecology-- Fresh water ecology-- Pond ecology-- Limnology 66 Aquatic biology, organisms, plankton, freshwater biology 65 Manual 65 Annals of Mathematics Studies 55 History 51 Aquatic ecology-- Fresh water ecology-- Pond ecology-- Limnology (biology)-- groundwater ecology 49 Handbooks 49 Chemistry 41 Aquatic ecology 40 Research 40 Water pollution-- Aquatic ecology 40 methods 40 Microbiology 36 Literature 35 Electronics-Laboratory Manuals 33 Aquatic ecology-- Fresh water ecology-- Pond ecology-- Limnology (biology)-- groundwater ecology-- Periph 32 Chemistry, Organic 32 Handbook 31 Handbooks, manuals etc 29 Ecology 28 SCIENCES 28 Analysis 27 Criticism and interpretation 27 English language 27 History and criticism 26 Laboratory manual 25