Thomas, Joseph, author
Philadelphia : J.B. Lippincott, 1915
Buku Referensi
Sykes, Egerton, author
London, J.M. Dent and Sons
Buku Referensi
Reinbek bei Hamburg Rowohlt Taschenbuch Verlag GmbH 1988
Buku Teks
Jones, Daniel, author
Cambridge University Press, 2003
Buku Teks
Jones, Daniel, author
Cambridge University Press, 1992
Buku Referensi