Hays, Samuel
London Longmans, Green and Co. 1953,
Buku Teks
Hays, William L.
Holt, Rinehart and Winston, 1971
Buku Teks
Freund, John E., author
McGraw-Hill, c1966
Buku Teks
Spiegel, Murray R., author
McGraw-Hill, 1992
Buku Teks
Spiegel, Murray R., author
McGraw-Hill, 1987
Buku Teks