Runyon, Richard P., author
Ill. Richard D. Irwin , 1982
Buku Teks
Walpole, Ronald E., author
Macmillan, 1968
Buku Teks
Freund, John E., author
Prentice-Hall, 1980
Buku Teks
Allen, R.G.D., author
Hutchinson University Library, 1972
Buku Teks
Salkind, Neil J., author
Sage, 2000
Buku Teks