Greenlaw, Paul S.
New York, N.Y. Harper & Row 1986,
Buku Teks
Sikula, Andrew F.
Cal Wiley, 1976
Buku Teks
Strauss, George, author
Prentice-Hall, 1980
Buku Teks
Strauss, George, author
Prentice Hall of India, 1985
Buku Teks
Byars, Llyod L., author
Richard D. Irwin, 1984
Buku Teks