Porter, Michael E.
Free Press, 1980
Buku Teks SO
Bisnis & Birokrasi: Jurnal Ilmu Administrasi dan Organisasi, 16 (1) Jan-Apr 2009: 45-52,
Artikel Jurnal
Walker, Gordon
Irwin, McGraw-Hill, 2004
Buku Teks
Haynes, W. Warren [William Warren], 1921-1972
Prentice-Hall, 1961
Buku Teks
edited by Robert H. Doktor, Michael A. Moses
Prentice-Hall, 1973
Buku Teks