Book 16,714 Government Document 3,980 Map 2,610 Electronic 1,130 Conference Proceeding 916 Serial 814 Journal 578 Thesis 300 Unknown 190 Kit 47 Reference Material 35 Photo 32 Book Chapter 26 Manuscript 12 Audio 10 Article 8 Newspaper 5 Musical Score 2 see all ...

T - Technology 6,114 H - Social Science 2,079 Q - Science 1,928 G - Geography, Anthropology, Recreation 1,296 C - Historical Sciences 989 K - Law 660 U - Military Science 299 P - Language and Literature 154 L - Education 105 Z - Library Science 103 D - World History 99 E - United States History 96 J - Political Science 67 F - General American History 65 V - Naval Science 61 A - General Works 50 N - Fine Arts 43 R - Medicine 32 S - Agriculture 29 M - Music 21 B - Philosophy, Psychology, Religion 15 see all ...

Geological Survey (U.S.) 1,227 Library of Congress Congressional Research Service 642 American Association of Petroleum Geologists 272 United States Bureau of Mines 233 Adam Matthew Digital (Firm) 221 American Society for Testing and Materials 218 ASTM International 206 Foreign Office 196 Petroleum Economist Ltd 196 United States Congress 157 Fuller, K 134 Bush, P 123 United States Congress. House. Committee on Interstate and Foreign Commerce 121 American Petroleum Institute 109 United States General Accounting Office 106 United States Congress. House. Committee on Ways and Means 100 United States 99 Petroleum Economist Cartographic (Firm) 97 United States Congress. Senate. Committee on Interior and Insular Affairs 93 Geological Society of London 90 United States Department of Energy 90 Institute of Petroleum (Great Britain) 83 United States Congress. Senate. Committee on Finance 79 United States Congress. Senate. Committee on Energy and Natural Resources 77 United States Congress. Joint Committee on Taxation 71 American Chemical Society Division of Petroleum Chemistry 62 United States Energy Information Administration. Office of Oil and Gas 62 Australia Bureau of Mineral Resources, Geology and Geophysics 61 Institut geologii i razrabotki gori︠u︡chikh iskopaemykh (Russia) 61 Illinois State Geological Survey 59 see all ...

English 18,063 Russian 912 Spanish 604 French 495 German 404 Chinese 317 Hebrew 156 Arabic 141 Portuguese 110 Japanese 99 Indonesian 57 Italian 51 Persian 43 Dutch 26 Turkish 26 Polish 22 Vietnamese 21 Romanian 20 Danish 18 Thai 14 Undetermined 13 Multiple 11 Azerbaijani 10 Korean 8 Norwegian 6 Ukrainian 6 Hindi 5 Swedish 5 Uighur 5 Croatian 4 see all ...

Maps 2,572 Congresses 994 Periodicals 881 Conference papers and proceedings 623 Electronic books 489 Statistics 468 History 247 Bibliography 188 Thematic maps 168 Charts, diagrams, etc 137 Dictionaries 129 Geological maps 114 Guidebooks 67 Handbooks, manuals, etc 62 Bibliographies 59 Documentary films 55 Legislative hearings 55 Tables 54 Legislative materials 51 Electronic journals 49 Handbooks and manuals 49 Academic theses 47 Legislative histories 47 Internet videos 42 Video recordings 42 Biography 39 Government publications 38 CD-ROMs 37 Drama 37 Congress 36 see all ...

Cretaceous 112 20th century 102 Paleozoic 85 Ottoman Empire, 1288-1918 80 Mesozoic 66 Mississippian 60 Devonian 59 Permian 54 Ordovician 47 Silurian 44 From 65 to 140 million years ago 42 Cenozoic 41 1900-1999 40 Jurassic 39 Tertiary 39 Pennsylvanian 31 Carboniferous 30 From 310 to 345 million years ago 29 21st century 26 Cambrian 26 Eocene 26 Miocene 26 19th century 25 From 230 to 570 million years ago 23 Precambrian 19 1861-1944 16 From 65 to 230 million years ago 14 From 405 to 425 million years ago 13 Paleocene 13 From 2 to 65 million years ago 12 see all ...

United States 3,517 California 535 China 534 Alaska 489 Texas 434 Canada 320 Iran 320 Russia (Federation) 312 Pennsylvania 302 Mexico 289 Russia 287 Wyoming 287 India 274 Middle East 274 North Dakota 267 France 233 Asia, Central 225 Soviet Union 220 Afghanistan 218 Germany 217 Oklahoma 210 Turkey 194 Kansas 193 Central Asia 191 Australia 185 Illinois 181 Japan 181 New Mexico 181 Khanate of Bukhara 177 Caspian Sea 171 see all ...