Richard Henry Popkin. (1993). Philosophy made simple. New York: Doubleday.
Dyfyniad Arddull ChicagoRichard Henry Popkin. Philosophy Made Simple. New York: Doubleday, 1993.
Dyfyniad MLARichard Henry Popkin. Philosophy Made Simple. New York: Doubleday, 1993.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.