Brown, Brian
Open University Press, 2003
Buku Teks
Brant, Xenia Maria Caldeira, editor
Springer, 2012
eBooks
Swage, Thoreya
Butterworth-Heinemann , 2004
Buku Teks
Muhammad Ameerul Amin Bakar
UMT, 2017
Artikel Jurnal
Cama, Rosalyn
John Wiley & Sons, 2009
Buku Teks SO