Moore, Wilbert E. (Wilbert Ellis), author
Macmillan, 1955
Buku Teks
DuBrin, Andrew J., author
Prentice-Hall, 2000
Buku Teks
Prentice-Hall, 1949
Buku Teks
Dunlop, John T., author
Holt, 1958
Buku Teks
Rose, Ed (Edward), 1946-, author
Prentice-Hall, 2001
Buku Teks