Williamson, T. (2009). Brief History of Time.
Lua i Stíl Chicago (17ú heag.)Williamson, T. Brief History of Time. 2009.
Lua MLA (9ú heag.)Williamson, T. Brief History of Time. 2009.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.