Shayne Cox Gad.
Wiley-Interscience , 2017
Buku Referensi
Sobti, R.C.
CRC Press, Taylor & Francis Group, 2009
Buku Teks
edited by Martin Fransman, Gerd Junne and Annemieke Roobeek
Blackwell, 1995
Buku Teks
Barnum, Susan R.
Wadsworth, 1998
Buku Teks
Kayser, Oliver
Wiley-VCH, 2004
Buku Teks