New Delhi, India : Indian Council for Cultural Relation
Majalah, Jurnal, Buletin
Aldine Publishing Company, 1964
Buku Teks SO
Simpson, W.O.
Stanley Thornes, 1986
Buku Teks
Barnes, Harry Elmer
Prentice Hall of India, 1966
Buku Teks
edited by Gerald W. Whitted
Pan American World Airways, 1971
Buku Referensi