Berkey, Charles Peter. "Geology of the New York City (Catskill) aqueduct; studies in applied geology covering problems encountered in explorations along the line of the aqueduct from the Catskill Mountains to New York City." Book. 1911. Columbia Digital Library Collections [Columbia University Libraries]. Accessed 18 Apr 2024. https://doi.org/10.7916/d8-9v0r-2s70