Allen, Shirley Walter
Conserving natural resources principles and practice in a democracy
McGraw-Hill , 1959
 Buku Teks
Burke, Mary A.
Organization of multimedia resources: principles and practice of information retrieval
Gower , 2001
 Buku Teks
Catt, Helena
Democracy in practice
Routledge , 1999
 Buku Teks
Le Boutillier, Cornelia Geer
American democracy and natural law
Columbia University Press, 1950
 Buku Teks
Pearce, David William, 1941-
Economics of natural resources and the environment
Harvester Wheatsheaf, 1990
 Buku Teks