^Steingress, Frederick M. (). Low Pressure Boilers (ed. 4th Edition). American Technical Publishers. ISBN0-8269-4417-5.Mentenanță CS1: Text în plus (link)
^Steingress, Frederick M. (). High Pressure Boilers (ed. 3rd Edition). American Technical Publishers. ISBN0-8269-4300-4.Mentenanță CS1: Text în plus (link)