Seibert, Joseph C., author
Harper and Row, 1972
Buku Teks
Tony Kent, Reva Brown, editor
Routledge, 2009
Buku Teks
Schewe, Charles D., author
McGraw-Hill, 1983
Buku Teks
Hise, Richard T., author
Winthrop, 1979
Buku Teks
Blythe, Jim, author
Sage Publications, 2012
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