Russell, Robert, 1924-2011, author
Vanguard Press, 1962
Buku Teks
Gavell, Mary Ladd, author
Random House Trade Paperbacks, 2001
Buku Teks
Gavell, Mary Ladd, author
Random House Trade Papaerbacks, 2001
Buku Teks
Artikel Jurnal
Guaspari, John, author
American Society for Training & Development, 1985
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