Zikmund, William G., author
The Dryden Press , 1991
Buku Teks
Lorie, James H., author
NMcGraw-Hill , 1951
Buku Teks
American Institutes For Research
American Institutes For Research, 1970
Buku Teks
Goode, William J., author
McGraw-Hill, 1952
Buku Teks
by Claire Selltiz [and others]
Holt, Rinehart and Winston, 1959
Buku Teks