Burke
Avon Book Division, 1965
Buku Teks
Bluhm, William T
Prentice Hall of India, 1981
Buku Teks
Ebenstein, William, author
Holt, Rinehart and Winston, 1962
Buku Teks
Ebenstein, William, author
Rinehart, 1963
Buku Teks
Ebenstein, William, author
Thomson Learning, 2000
Buku Teks