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