Maclean, James H., author
Penguin Books, 1993
Buku Referensi
Bannock, G., author
Penguin Books, 1974
Buku Referensi
Thomas, Merlin, author
Penguin Books, 1985
Buku Referensi
Bannock, G., author
Allen Lane / The Viking Press, 1979
Buku Referensi
Bryson, Bill, author
Penguin Books, 1994
Buku Referensi