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Dyfyniad Arddull ChicagoE.P.A. Handbook of Ground Water. Jodhpur: Scientific Publishers, 1994.
Dyfyniad MLAE.P.A. Handbook of Ground Water. Scientific Publishers, 1994.
Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.