Dyfyniad APA
Hawking, S. W., & Penrose, R. (2010). The nature of space and time (13th print.). Princeton University Press.
Dyfyniad Arddull Chicago
Hawking, S. W., and Roger Penrose. The Nature of Space and Time. 13th print. Princeton, N.J.: Princeton University Press, 2010.
Dyfyniad MLA
Hawking, S. W., and Roger Penrose. The Nature of Space and Time. 13th print. Princeton University Press, 2010.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.