Bollens, John C., author
Harper and Row, 1975
Buku Teks
Bollens, John C., author
Harper and Row, 1970
Buku Teks
edited by Leonard J. Duhl, with the assistance of John Powell
Basic Books, 1963
Buku Teks
Marshall, Dale Rogers
Resorces for the future, 1972
Buku Teks
Gilham, Oliver
Islan Press, 2002
Buku Teks