Tichelmann, Karsten
Birkhauser GmbH, 2008
Buku Referensi
Thiede, Sebastian
Springer, 2012
eBooks
Duran, Sergi Costa
Page One Publishing, 2011
Buku Referensi
Dean, Norman L.
Ballinger, 1980
Buku Teks
Flavin, Christopher
Worldwatch Institute, 1988
Buku Teks