Gage Educational Publishing Limited, 1976
Buku Teks
Buckley, Roger
Cambridge University Press, 1990
Buku Teks
International Society for Educational Information, 1989
Buku Teks
Woodhead, H. G. W. (Henry George Wandesforde)
E. P. Dutton, 1914
Buku Teks
The Commercial Press, 1939
Buku Teks