12/12/1901 Mallory, Walter Seeley to American School of Correspondence
(Edison Portland Cement Co) Education; Labor; Ore milling and separation
[LM243]  Company Records Series -- New Jersey and Pennsylvania Concentrating Works -- Letterbooks -- Walter S. Mallory Letterbooks: LM-243 (July 1901-June 1902)
[LM243491; TAEM 154:200]
Courtesy of Thomas Edison National Historical Park.