Classificação da Biblioteca do Congresso dos E.U.A. (LCC)GB635.I6

adventure(25) Africa(10) American West(10) animals(102) Antarctic(5) anthropology(13) archaeology(18) biography(16) biology(35) birds(9) botany(10) Canada(6) cave(17) caves(447) chemistry(5) children(25) children's(41) climate(21) climate change(21) climbing(5) conservation(11) curriculum(5) desert(160) deserts(164) discovery(5) earth(65) easy reader(9) ecology(68) ecosystems(27) education(10) Egypt(6) elementary(6) environment(71) exploration(38) family(5) geography(233) geology(278) Grade 2(6) guide(6) guidebook(15) hiking(10) history(84) informational(40) insects(8) juvenile(16) juvenile literature(5) juvenile non-fiction(10) Kentucky(21) kids(13) land(6) learning(5) life science(8) Mexico(10) middle grade(6) Minnesota(10) modern history(5) music(7) National Parks(16) natural science(10) natural world(6) nature(242) nature writing(5) New Mexico(13) North America(8) outdoors(18) photographs(17) photography(55) picture book(57) prehistory(7) primary(6) recreation(5) reference(38) reptiles(10) rivers(17) sand(12) science(589) science nonfiction(5) sets(5) social studies(12) Southwest(15) sport(8) sports(5) Subterranean(12) swamp(38) technique(5) Tennessee(5) Texas(9) tourism(5) travel(118) travel writing(5) underground(10) us(8) US travel(6) usa(31) Virginia(6) weather(7) wildlife(17) world(6)