Steve A. Johnson (1984), "Ibn Sina's Fourth Ontological Argument for God's Existence", The Muslim World 74 (3-4), 161–171.
ISSN 1095-5054.  필요 이상의 변수가 사용됨: |저자= 및 |성= (도움말) Steve A. Johnson (1984), "Ibn Sina's Fourth Ontological Argument for God's Existence", The Muslim World 74 (3-4), 161–171.