Periodicals 492 Bibliography 416 Libraries 236 Library science 233 Books 149 History 90 Science 73 more ... Government publications 72 Education 66 Printing 61 Information science 56 Dissertations, Academic 55 Imprints 49 Indexes 47 Agriculture 46 Information storage and retrieval systems 46 Publishers and publishing 45 Documentation 44 Social sciences 44 Research 41 Literature 40 Medicine 39 Technology 37 Abstracts 36 History and criticism 36 Humanities 36 Catalogs 35 Children's literature 35 Information services 35 Philosophy 35 less ...