Peter Pierce, Rosemary Hunter, editor
Oxford Univeristy Press, 1987
Buku Referensi
general editor: Laurie Hergenhan ; editors : Bruce Bennett ... [et al.]
Penguin Books, 1988
Buku Teks SO
Oxford University Press, 1969
Koleksi Publik
Spate, Oskar Hermann Kristian
Ernest Benn, 1968
Buku Teks SO
Crawford, R.M.
Hutchinson's University Library, 1955
Buku Teks SO