Yusuf Hadli
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2014
UI - Skripsi Membership
Rucker, Bryce W.
The Iowa State Univ. Press, 1964
Buku Teks
Izard, Halph S.
Hunt Publishing Company, 1977
Buku Teks
MacDougall, Curtis D.
Macmillan, 1967
Buku Teks SO
Pilger, John
Vereso, 2002
Buku Teks