Huffman, Karen
John Wiley & Sons, 1997
Buku Teks SO
Hartman, Philip E.
Prentice Hall of India Private Limited, 1972
Buku Referensi
Beneficial Management Institute, [Date of publication not identified]
Buku Teks
Learned, Edmund P. (Edmund Philip), 1900-1991
Andover Press, 1957
Buku Teks SO
Hayakawa, S.I.
Harcourt, Brace, 1940
Buku Teks SO