Brammer, Robert
Brooks/Cole Cengage Learning, 2012
Buku Teks SO
Brammer, Robert
Thomson, 2004
Buku Teks SO
Arbuckle, Dugald S.
Allyn and Bacon, 1961
Buku Teks
editor, Don C. Locke, Jane E. Myers, Edwin L. Herr
Sage, 2001
Buku Referensi
Einstein, Mara
Lawrence Erlbaum, 2004
Buku Teks