(1970). Conservation directory 1971: A listing of organizations, agencies and officials concerned with natural resource use and management. Washington, D.C: The National Wildlife Federation.
Παραπομπή Chicago StyleConservation Directory 1971: A Listing of Organizations, Agencies and Officials Concerned With Natural Resource Use and Management. Washington, D.C: The National Wildlife Federation, 1970.
Παραπομπή MLAConservation Directory 1971: A Listing of Organizations, Agencies and Officials Concerned With Natural Resource Use and Management. Washington, D.C: The National Wildlife Federation, 1970.
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