Penniman, Howard R., author
D. Van Nostrand, 1962
Buku Teks
Kendall, Willmoore, author
Louisiana University Press, 1970
Buku Teks
Plano, Jack C., author
Holt, Rinehart and Winston, 1985
Buku Referensi
Cummings, Milton C.
Harcourt Brace Jovanovich, 1981
Buku Teks
Cummings, Milton C.
Harcourt Brace Jovanovich, 1977
Buku Teks