Paul M. Camic, Jean E. Rhodes, Lucy Yardley
APA, 2007
Buku Teks SO
Lewis, Michele K.
Springer, 2012
eBooks
edited by Pieter J.D. Drenth, Joseph A. Sergeant, Roelf J. Takens
John Wiley & Sons, 1990
Buku Teks SO
Alloy, Lauren B.
McGraw-Hill , 1999
Buku Teks SO
Feist, Gregory J.
McGraw-Hill, 2012
Buku Teks SO