Rolf, Christer, author
A & C Black, 2007
Buku Referensi
Milroy, Patrick, author
Ward Lock Book, 1994
Buku Referensi
Pennsylvania Elsevier, 2015
Buku Teks
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
Kennedy, David, author
Bay Books, 1988
Buku Referensi