Kantor Penerbangan India,
Buku Teks
Spear, Percival, author
The University of Michigan Press, 1961
Buku Teks
Chandra, Bipan
National Council of Educational Research and Training, 1971
Buku Teks
Smith, Vincent A.
The Clarendon Press, 1958
Buku Teks
Lamb, Beatrice Pitney
Frederick A. Praeger , 1968
Buku Teks