Kongressin kirjaston luokitusQH540-549.5

agriculture(68) animals(2,600) beach(115) biology(1,771) birds(264) botany(174) children(374) children's(470) climate(108) climate change(139) communities(33) conservation(381) desert(255) deserts(181) earth(217) ecology(4,124) ecosystems(504) education(101) educational(50) elementary(79) energy(62) environment(1,845) environmental(130) environmental issues(28) environmental studies(68) environmentalism(348) environments(42) evolution(602) extinction(83) fish(198) forest(305) gardening(182) general science(44) geography(442) geology(88) Grade 2(53) green(72) history(232) human ecology(47) informational(275) informative(39) insects(232) islands(64) juvenile(183) juvenile non-fiction(98) kids(137) life cycle(58) life science(253) Life Sciences(40) mammals(59) marine(64) marine life(48) mimicry(28) natural resources(33) natural science(115) natural world(34) nature(3,198) nature writing(85) ocean(568) oceanography(79) oceans(195) picture book(949) pollution(214) pond(155) ponds(215) popular science(61) populations(32) prairie(86) reference(264) reptiles(68) rivers(173) science(6,056) science nonfiction(89) sea(93) sea life(75) statistics(86) sustainability(163) swamp(89) symbiosis(78) trees(397) tropical(33) wildlife(222) woods(69)