Dannley, Ralph L.
Macmillan, 1968
Buku Teks
Fishel, Derry L.
Macmillan, 1971
Buku Teks
by Royston M. Roberts ... [et al.]
Rinehart and Winston, 1969
Buku Teks
Wilcox, Charles F., 1930-
Prentice-Hall, 1995
Buku Teks
Singh, P.R.
Tata McGraw-Hill, 1980
Buku Teks