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.
Dyfyniad Arddull Chicagoebrary, Inc, and 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.
Dyfyniad MLAebrary, Inc, and John F. Wippel. The Ultimate Why Question: Why Is There Anything at All Rather than Nothing Whatsoever? Catholic University of America Press, 2011.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.