Podis, Leonard A., author
Scott, foresman and Company3, 1983
Buku Referensi
William Warren ... [and others] ; phographer, Luca Invernizzi Tettoni
Periplus editions, 1997
Buku Referensi
Winter, Robert, author
Simon & Schuster, 1996
Buku Referensi
Lindawaty, author
Fakultas Ekonomi dan Bisnis Universitas Indonesia, 2011
UI - Tesis (Open)
Kernighan, Brian W., author
McGraw-Hill , 1974
Buku Teks