Concerning Mike Paradis' inquiry - who are "H.E. Stone" and "S.D. Stone" of Morgantown, WV:
Harry E. Stone was born Dec. 31, 1883, Corry, Erie County, PA - Died January 31, 1959, Morgantown, WV.
His wife was Sarah Day Stone (born 1884, PA - died March 23, 1949, Morgantown, WV)
Starting in 1920's, Harry E. Stone was a Dean at West Virginia University in Morgantown until his death. Before that he had been a teacher various places in PA.
No mention is made of him being a coin and stamp dealer. Possibly a collector and not dealer. Maybe this is not correct person; but seems likely to me.
Sure seems like a likely match! Mike Paradis provided an image of the letterhead which prompted his question.