Dyfyniad APA

Stephen Hawking (Great Neck Publishing). Great Neck Publishing.

Dyfyniad Arddull Chicago

Stephen Hawking (Great Neck Publishing). Great Neck Publishing.

Dyfyniad MLA

Stephen Hawking (Great Neck Publishing). Great Neck Publishing.

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