Jennings, Lucy Mae
Prentince-Hall, 1983
Buku Teks
Ochs, Linnea Leedham, author
Prentice-Hall, 1987
Buku Referensi
edited by Coleen K. Withgott, Austin G. Anderson
Merriam-Webster, 1981
Buku Referensi
Bredow, Miriam, author
Gregg Publishing, 1959
Buku Referensi
Wisinski, Jerry, author
[American Management Association, ], 1999
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