Simanjuntak, Sangap Prawira
Fakultas Ilmu Sosial dan Ilmu Politik Universitas Indonesia, 2004
UI - Tesis (Membership)
Allen, Peter
Pitman, 1998
Buku Teks
Rodgers, Mark
McGraw-Hill , 2011
Buku Teks
Wingate, John W.
South-Western Publishing, 1959
Buku Teks
Allen, Robert Y.
McGraw-Hill, 1984
Buku Teks