Spear, Percival
Oxford University Press, 1949
Buku Teks
Lamb, Beatrice Pitney
Frederick A. Praeger , 1968
Buku Teks
Philips, C.H.
Hutchinson University Library , 1949
Buku Teks
Kantor Penerbangan India,
Buku Teks
Valth, Alfons
Herder & co. g. m. b. h, 1934
Buku Teks