Ahmad, Fazl. Omar : The Second Caliph of Islam / by Fazl Ahmad. - Rev ed. - Lahore, Pakistan : sh. muhammad ashraf, 1973 [reprinted 1975]. - 101 p. ; 18 cm. - Heroes of Islam ; 3 . Subjects--Personal Names: Umar II, Caliph, d. 720. LC Class. No.: DS238.U5 / A6 1975