CROCKETT, J. U. (1978). Bulbs James Underwood Crockett. Time Life Books.
Dyfyniad Arddull ChicagoCROCKETT, James Underwood. Bulbs James Underwood Crockett. Time Life Books, 1978.
Dyfyniad MLACROCKETT, James Underwood. Bulbs James Underwood Crockett. Time Life Books, 1978.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.