edited by Tony Smith
Dorling Kindersley, 1990
Buku Referensi
Eliopoulos, Charlotte, author
Jones & Bartlett Learning, 2010
Buku Teks
edited by Tony Smith
Dorling Kindersley, 1995
Buku Referensi
Allan, David M., author
McGraw-Hill, 2008
Buku Teks
Youngson, Robert
Bloomsbury, 1995
Buku Referensi