Dunlop, John T.
Holt, 1958
Buku Teks
Yoder, Dale
Prentice-Hall, 1962
Buku Teks
Yoder, Dale
Prentice-Hall, 1984
Buku Teks
edited by Suresh P. Sethi, Marija Bogataj and Lorenzo Ros-McDonnell
Springer, 2012
eBooks
Moore, Wilbert Ellis
Macmillan, 1955
Buku Teks