Reading, Hugo F.
Routledge & Kegan Paul, 1978
Buku Teks
Buku Teks
edited by R.N. Chopra
Anmol Publications, 1992
Buku Referensi
Porteous, Andrew
John Wiley & Sons, 1992
Buku Referensi
edited by W.F. Bynum, E.J. Browne, Roy Porter
Macmillan Reference Books, 1989
Buku Referensi