Bradsher, Earl L.
The Columbia University Press, 1912
Buku Teks
Universitas Indonesia, 2014
UI - Skripsi (Membership)
Simone, Luisa
Microsoft Press, 1992
Buku Teks
Edited by Eleanor Harman
University of Toronto, 1961
Buku Teks
Klose, Paul S.
Dow Jones-Irwin, 1989
Buku Referensi