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Dyfyniad Arddull ChicagoPneumoconiosis; Proceedings of the International Conference, Johannesburg, 1969. Edited by H.A. Shapiro. 1970.
Dyfyniad MLAPneumoconiosis; Proceedings of the International Conference, Johannesburg, 1969. Edited by H.A. Shapiro. 1970.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.