Heimstra, Norman W.
Brooks/Cole, 1974
Buku Teks
by Paul A. Bell ... [and others]
Wadsworth/Thomson Learning, 2001
Buku Teks
Bell, Paul A.
Thomson, 2001
Buku Teks
Paul A. Bell ... [and others]
Harcourt Brace College, 1996
Buku Teks
Nickerson, Raymon S.
Lawrence Erlbaum Associates, 2003
Buku Teks