Thakur, Ramesh
London: Westview Press, 1986,
Buku Referensi
Barber, Laurie
Century Hutchinson, 1989
Buku Teks
Sinclair, Keith
Penguin Books, 1986
Buku Teks SO
Sinclair, Keith
Penguin Books, 1960
Buku Teks SO
Barber, Laurie
Century Hutchinson, 1989
Buku Teks SO