Bowers, David A., author
Prentice-Hall, 1971
Buku Teks
by edited by David F. Heathfield
Macmillan, 1976
Buku Teks
Allen, R.G.D., author
Macmillan, 1973
Buku Teks
Blanchard, Olivier, author
Pearson, 2009
Buku Teks
Blanchard, Oliver, author
Prentice-Hall, 1997
Buku Teks