Priestley, J. B. (John Boynton), 1894-1984, author
Alison & Busby, 1968
Buku Teks
Firth, John Rupert, author
Watts, 1937
Buku Teks
Bell, E.T.
Simon & Schuster, 1986
Buku Teks
editor, Ernest Kay
Melrose Press Ltd., 1995
Buku Referensi
Braidwood, Robert J., author
Natural History Museum, 1963
Buku Teks