Eulau, Heinz, author
Bobbs-Merrill, 1963
Buku Teks
Tansey, Stephen D., author
Routledge, 1996
Buku Teks
Combs, James E., author
Macmillan, 1984
Buku Teks
Dyke, Vernon van, author
Nelson, 1992
Buku Teks
Merriam, Charles E. (Charles Edward), author
University of Chicago Press, 1957
Buku Teks