Barback, R.H.
Philip Allan Publishers , 1984
Buku Teks
Mackintosh, A.S.
Cambridge University Press , 1963
Buku Teks
Florence, P. Sargant
Sweet & Maxwell, 1961
Buku Teks
Jervis, F.R., author
Routledge and Kegan Paul , 1971
Buku Teks
Atterbury, Paul
Hurtwood Press, 1985
Buku Teks