Gibbs Philip. (1930). Since then. London: William Heinemann.
Dyfyniad Arddull ChicagoGibbs Philip. Since Then. London: William Heinemann, 1930.
Dyfyniad MLAGibbs Philip. Since Then. London: William Heinemann, 1930.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.