Dyfyniad APA

Hester,Jeff, & Hester, J. J. (2007). 21st century astronomy (2nd ed.). New York: W.W. Norton.

Dyfyniad Arddull Chicago

Hester,Jeff, và John Jeffrey Hester. 21st Century Astronomy. 2nd ed. New York: W.W. Norton, 2007.

Dyfyniad MLA

Hester,Jeff, và John Jeffrey Hester. 21st Century Astronomy. 2nd ed. New York: W.W. Norton, 2007.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.