Longley, Dennis, author
Macmillan, 1982
Buku Referensi
Jones, Graham, author
McGraw-Hill, 1988
Buku Teks
Gunton, Tony, author
NCC Blackwell, 1993
Buku Teks
Manuel Gausa, Vicente Guallart, Willy Muller, Federico Soriano, Fernando Porras, Jose Morales
ACTAR, 2003
Buku Referensi
Pugh, Eric, author
Oryx Press, 1981
Buku Referensi