Duff, Lois, author
Longman, 1997
Buku Teks
edited by Randolph L. Braham
Alfred A. Knopf, 1966
Buku Teks
Ehrenberg, Ronald G., author
Pearsons Addison-Wesley , 2009
Buku Teks
Starling, Grover, author
Dorsey Press, 1979
Buku Teks
Allen, Clark Lee, author
McGraw-Hill, 1954
Buku Teks