Still, Brian, author
CRC press, 2017
eBooks
Harvey, Ross, author
London Bowker Saur , 1992
Buku Teks
O`Hagan, Kieran, author
Open University Press, 2006
Buku Teks
Gates, Jean Key, author
McGraw-Hill, 1974
Buku Referensi
Curzon, Susan Carol, author
Facet Publishing, 2006
Buku Teks