Spindler, Karlheinz
Marcel Dekker, 1994
Buku Teks
Gilligan, Lawrence G., author
D.C. Heath, 1985
Buku Teks
Hillman, Abraham P.
PW Publishing Company, 1994
Buku Teks
Aiken, Daymond J.
"New York: McGraw-Hill, 1957",
Buku Teks
Flanders, Harley, author
Academic Press, 1975
Buku Teks