Taylor, A.H., author
Pan Books , 1972
Buku Teks
Halford, D.R.C., author
Pan Books, 1971
Buku Teks
Velasquez, Manuel G
Prentice-Hall, 2002
Buku Teks
Phillips, Robert, 1968-, author
Berrett-Koehler, 2003
Buku Teks
Carroll, Archie B., author
Thomson , 2003
Buku Teks