Porter, Lindsay, author
Porter Publishing, 1995
Buku Referensi
White, Charles, author
Haynes Publishing, 1992
Buku Referensi
Porter, Lindsay, author
Haynes Publishing, 1991
Buku Referensi
Michael G. Grantham, editor
Routledge, 2011
Buku Teks
Escoe, A. Keith
Elsevier, 2008
Buku Teks