Oliver, Roland
Penguin Books , 1966
Buku Teks
Oberdorfer, Don, author
Basic Books, 2001
Buku Teks
Fage, J.D., author
Routledge, 1995
Buku Teks
Hatch, John, author
Frederick A. Praeger, 1965
Buku Teks
edited by Gerald Moore and Ulli Beier
Penguin Books, 1963
Buku Teks