National water well Association. (1985). Well drilling manual. National water well Association.
Παραπομπή Chicago StyleNational water well Association. Well Drilling Manual. India: National water well Association, 1985.
Παραπομπή MLANational water well Association. Well Drilling Manual. National water well Association, 1985.
Πρόσοχή: Οι παραπομπές μπορεί να μην είναι 100% ακριβείς.