Milroy, Patrick, author
Ward Lock Book, 1994
Buku Referensi
Rolf, Christer, author
A & C Black, 2007
Buku Referensi
Peter Brukner, Ben Clarsen, Jill Cook, Ann Cools, Kay Crossley, Mark Hutchinson, Paul McCrory, Roald Bahr, Karim Khan, authors
McGraw-Hill Education , 2017
Buku Teks
Brukner, Peter, author
McGraw-Hill, 2014
Buku Teks
Kennedy, David, author
Bay Books, 1988
Buku Referensi