Greenlaw, Paul S.
Harper & Row, 1986
Buku Teks
Sikula, Andrew F.
Cal Wiley, 1976
Buku Teks
Straus, George, author
Prentice-Hall, 1967
Buku Teks
Strauss, George, author
Prentice-Hall, 1980
Buku Teks
Strauss, George, author
Prentice Hall of India, 1985
Buku Teks