Dibben, Damian
Mizan Media Utama, 2015
Buku Teks SO
Vilsen, Luc
Descle de Brouwer, 1969
Buku Teks
Brant, Irving
Charter Books, 1963
Buku Teks
Payne, Robert
Macmillan, 1951
Buku Teks
edited by John Keep with the assistance of Liliana Brisby
Frederick A. Praeger, 1964
Buku Teks SO