ebrary, Inc, & Wippel, J. F. (2011). The ultimate why question: Why is there anything at all rather than nothing whatsoever? Catholic University of America Press.
Чикаго стиль цитування (17-те видання)ebrary, Inc, та John F. Wippel. The Ultimate Why Question: Why Is There Anything at All Rather than Nothing Whatsoever? Washington, D.C.: Catholic University of America Press, 2011.
Стиль цитування MLA (9-ме видання)ebrary, Inc, та John F. Wippel. The Ultimate Why Question: Why Is There Anything at All Rather than Nothing Whatsoever? Catholic University of America Press, 2011.
Попередження: стилі цитування не завжди правильні на всі 100%.