Gilmer, B. von Haller (Beverly von Haller), 1909-1994
McGraw-Hill, 1967
Buku Teks
Duffy, Karen G.
Pearson Education, Inc., 2005
Buku Teks
Duffy, Karen G.
New Jersey, 2005
Buku Teks
Lefton, Lester A.
Allyn and bacon , 1997
Buku Teks
Wortman, Camille B.
McGraw-Hill, 1992
Buku Teks