Modeste, Naomi N.
Sage Publications, 1996
Buku Referensi
Murray, Ruth Beckmann, author
Prentice-Hall, 1985
Buku Teks
Naidoo, Jenniem], author
Bailliere Tindal Elsevier, 2011
Buku Teks
Insel, Paul M., author
McGraw-Hill, 2012
Buku Teks
Bomar, Perri J.
W.B. Saunders , 1996
Buku Teks