Kezuhudan Umar Abdul Aziz dan kesederhanaan Nik Abdul Aziz - Wan Ji Wan Hussin, 1982-; Safulamri M. Hussain (Petaling Jaya, Selangor : Penerbit Rijal Media, 2010)
Keywords: 'Umar ibn'Abd al-'Aziz, -- Caliph, -- d. 720; Nik Abdul Aziz Nik Mat, -- Dato' Haji, -- 1931-2015; Islamic leadership; Leadership -- Religious aspects -- Islam