Schweitzer, James A.
Butterworth, 1982
Buku Teks SO
Blanca Jimenez and Joan Rose, editor
CRC Press, Taylor & Francis Group, 2009
Buku Teks
Kanter, Jerome
Englewood Cliffs, N.J. Prentice-Hall 1992,
Buku Referensi
E. Wainright Martin ... [and others]
Pearson, 2002
Buku Teks
Cricket Liu; Jerry Peek; Russ Jones; Bryan Buus; Adrian Nye
O'Reilly, 1994
Buku Teks SO