{{sfn|Narlikar|Burbidge|2008|p=}}

* {{cite book | last=Narlikar | first=Jayant | last2=Burbidge | first2=Geoffrey | title=Facts and Speculations in Cosmology | publisher=Cambridge University Press | publication-place=Cambridge | date=2008-07-03 | isbn=978-0-521-86504-3}}

<ref name="u701">{{cite book | last=Narlikar | first=Jayant | last2=Burbidge | first2=Geoffrey | title=Facts and Speculations in Cosmology | publisher=Cambridge University Press | publication-place=Cambridge | date=2008-07-03 | isbn=978-0-521-86504-3 | page=}}</ref>