Gilmer, B. von Haller [Beverly von Haller], 1909-1994
McGraw-Hill, 1967
Buku Teks SO
Duffy, Karen G.
Pearson Education, Inc., 2005
Buku Teks SO
Lefton, Lester A.
Allyn and bacon , 1997
Buku Teks SO
Wortman, Camille B.
McGraw-Hill, 1992
Buku Teks SO
Myers, David G.
Worth, 1986
Buku Teks SO