Saari, Che Zarrina. 1998. “Al-Ghazalis Views on the Heart, the Spirit and the Soul: A Comparison Between Ihya’ ’Ulum Al-Din and Al-Risalah Al-Laduniyyah”. Jurnal Usuluddin 7 (June):193-208. http://mojes.um.edu.my/index.php/JUD/article/view/3301.