Houston, Brant
St. Martin Press, 1996
Buku Referensi
MacDougall, Curtis D.
Macmillan, 1967
Buku Teks SO
Izard, Halph S.
Hunt Publishing Company, 1977
Buku Teks
Rucker, Bryce W.
The Iowa State Univ. Press, 1964
Buku Teks
Yusuf Hadli
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2014
UI - Skripsi Membership