[The view of natural resources in the 20th                    century].
Zhang
Erxun
E
Qin
Yaochen
Y
D003247:Conservation of Natural Resources / Q000191:economics / Q000266:history / Q000331:legislation & jurisprudence; D004463:Ecology / Q000191:economics / Q000193:education / Q000266:history / Q000331:legislation & jurisprudence; D004777:Environment; D006077:Government Agencies / Q000191:economics / Q000266:history / Q000331:legislation & jurisprudence; D049673:History, 20th Century; D006808:Humanism / Q000266:history; D006801:Humans; D007390:International Agencies / Q000191:economics / Q000266:history / Q000331:legislation & jurisprudence; D008019:Life Style / Q000208:ethnology; D044382:Population Groups / Q000193:education / Q000208:ethnology / Q000266:history / Q000331:legislation & jurisprudence / Q000523:psychology; D011634:Public Health / Q000191:economics / Q000193:education / Q000266:history / Q000331:legislation & jurisprudence; D011639:Public Opinion; D012922:Social Change / Q000266:history