Wyatt, Stanley P.
Allyn and Bacon, 1971
Buku Teks
Hodge, Paul W.
McGraw-Hill, 1974
Buku Teks
Robbins, Robert R., author
John Wiley & Sons, 1981
Buku Teks
Wood, Harley
Angus and Robertson, 1967
Buku Teks
Hartman, William K., author
Wadsworth, 1985
Buku Teks