Daudistel, Howard C.
Holt, Rine hart and Winston, 1979
Buku Teks
Samaha, Joel
West Publishing, 1988
Buku Teks
Regoli, Robert M.
Jones and Bartlett Publishers, 2010
Buku Teks
Davis, Frederick T
Cambridge University Press, 2019
eBooks
Alpert, Geoffrey P.
Sage, 1985
Buku Teks