Wippel, J. F. (2011). The ultimate why question: Why is there anything at all rather than nothing whatsoever? Catholic University of America Press.
Cita Chicago Style (17a ed.)Wippel, John F. The Ultimate Why Question: Why Is There Anything at All Rather than Nothing Whatsoever? Washington, D.C.: Catholic University of America Press, 2011.
Cita MLA (8a ed.)Wippel, John F. The Ultimate Why Question: Why Is There Anything at All Rather than Nothing Whatsoever? Catholic University of America Press, 2011.
Precaución: Estas citas no son 100% exactas.