Dyfyniad APA

National water well Association. (1985). Well drilling manual. National water well Association.

Dyfyniad Arddull Chicago

National water well Association. Well Drilling Manual. India: National water well Association, 1985.

Dyfyniad MLA

National water well Association. Well Drilling Manual. National water well Association, 1985.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.