Ehlers, J. (1993). Canonical gravity: From classical to quantum. Springer-Verlag.
Lua i Stíl Chicago (17ú heag.)Ehlers, J. Canonical Gravity: From Classical to Quantum. New York: Springer-Verlag, 1993.
Lua MLA (9ú heag.)Ehlers, J. Canonical Gravity: From Classical to Quantum. Springer-Verlag, 1993.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.