Ballard, Robert D.
National Geographic Society, 1983
Buku Referensi
Chester, Roy
American Management Association, 2008
eBooks
Bowler, Sue
Erlangga, 2002
Buku Teks SO
Sutherland, Lin
University of New South Wales Press, 1995
Buku Referensi
Faundra Ihsan Pratama
Fakultas Teknik Universitas Indonesia, 2020
UI - Skripsi Membership