Tritton, A. (2002). Caliphs and their non-Muslim subjects: A critical study of the Covenant of `Umar. Idarah-I Adabiyat-I Delhi.
शिकागो शैली (17वां संस्करण) प्रशस्ति पत्रTritton, A.S. Caliphs and Their Non-Muslim Subjects: A Critical Study of the Covenant of `Umar. Idarah-I Adabiyat-I Delhi, 2002.
एमएलए (9वां संस्करण) प्रशस्ति पत्रTritton, A.S. Caliphs and Their Non-Muslim Subjects: A Critical Study of the Covenant of `Umar. Idarah-I Adabiyat-I Delhi, 2002.
चेतावनी: ये उद्धरण हमेशा 100% सटीक नहीं हो सकते हैं.