Spate, Oskar Hermann Kristian
Ernest Benn, 1968
Buku Teks SO
Crawford, R.M.
Hutchinson's University Library, 1955
Buku Teks SO
Berney, Maurice
Angus and Robertson, 1965
Buku Teks SO
Crawford, R.M.
Hutchinson University Library, 1952.
Buku Teks SO
Ward, Russel
Prentice-Hall, 1965
Buku Teks SO