Russell, Frederic A.
McGraw-Hill, 1988
Buku Teks SO
Buskirk, Richard Hobart, 1927-
McGraw-Hill, 1992
Buku Teks SO
Whiting, Percy H.
Dale Carnegie & Associates, 1979
Buku Teks SO
Sellars, David, III
Dryden Press, 1992
Buku Teks SO
Allen, Peter
Pitman, 1998
Buku Teks SO