Dyfyniad APA

Petroski, H. (1993). The evolution of useful things (First edition.). Alfred A.Knopf.

Dyfyniad Arddull Chicago

Petroski, Henry. The Evolution of Useful Things. First edition. New York: Alfred A.Knopf, 1993.

Dyfyniad MLA

Petroski, Henry. The Evolution of Useful Things. First edition. Alfred A.Knopf, 1993.

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