ISBN 81-206-0809-7* "Note by Professor H. A. R. Gibb" (1939), from Arnold J. Toynbee, "A Study of History", Part I.
ISBN 81-206-0809-7* "Note by Professor H. A. R. Gibb" (1939), from Arnold J. Toynbee, "بررسی تاریخ جهان", Part I.