Kislov, A.
Sterling Publishers Private, 1984
Buku Teks SO
Brown, A.J.
George Allen and Unwin, 1959
Buku Teks SO
United Nations Departemen of Public Information, 1990
Buku Teks
Perkins, J.O.N.
Sun Books, 1968
Buku Teks
Lougheed, Leslie Alan
Penguin Books, 1988
Buku Teks SO