edited by Jack Davis and Robert Lecker
General Publishing, 1982
Buku Teks
Lippincott , 2004
Buku Teks
Gall, Gerald B.
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Buku Teks
Buck, A. E., author
Public Administration Service, 1949
Buku Teks
edited by R.C. Bellan, W.H. Pope
McGraw-Hill, 1981
Buku Teks