Bauer, Richard C., author
Thomson, Brooks/Cole, 2005
Buku Teks
Cooper, Melanie M., author
McGraw-Hill, 2009
Buku Teks
Sackheim, George I., author
Macmillan, 1968
Buku Teks
by Horace D. Crockford [and others]
John Wiley & Sons, 1975
Buku Teks
Sousa, John J., author
Rhode Island Consortium, 1990
Buku Teks