Dyfyniad APA
Hester, J. J. (2007). 21st century astronomy (2nd ed.). W.W. Norton.
Dyfyniad Arddull Chicago
Hester, John Jeffrey. 21st Century Astronomy. 2nd ed. New York: W.W. Norton, 2007.
Dyfyniad MLA
Hester, John Jeffrey. 21st Century Astronomy. 2nd ed. W.W. Norton, 2007.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.