Clarendon Press, 1994
Buku Referensi
Crawley, Angela
Oxford University Press, 1994
Buku Referensi
edited by Thomas M. Paikeday
Holt, Rinehart and Winston, 1976
Buku Referensi
Oxford university press , 1992
Buku Teks
edited by P. S. Falla
Clarendon Press, 1990
Buku Referensi