Curiel, Erik & Peter Bokulich. "Singularities and Black Holes" 2 Eylül 2013 tarihinde Wayback Machine sitesinde arşivlendi.. Stanford Encyclopedia of Philosophy. Center for the Study of Language and Information, Stanford University. Retrieved 26 December 2012.
Curiel, Erik & Peter Bokulich. "Singularities and Black Holes" 2 Eylül 2013 tarihinde Wayback Machine sitesinde arşivlendi.. Stanford Encyclopedia of Philosophy. Center for the Study of Language and Information, Stanford University. Retrieved 26 December 2012.