Goldstein, E. Bruce
Cengage Learning, 2017
Buku Teks
Lorus, J.
Atheneum, 1962
Buku Teks
Goldstein, E. Bruce
Thomson Wadsworth, 2002
Buku Teks SO
Schiffman, Harvey Richard
John Wiley & Sons, 1982
Buku Teks SO
Roberts, Sam.
BBC Worldwide Limited, 2004
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