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Albert L. Toenges
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Paul Lewis Henderson
Clifford Jones
Unknown Author
Robert B. Finkelman
Turkey. Maden Tetkik ve Arama Genel Müdürlüğü
United Nations. Technical Assistance Administration.
Resources Research Committee
Robert Glenk
N. M. Denson
Edward C. Murphy
Ömer Hulusi Barutogl̆u
Harry L. Roland
General Report of the Lignite Utilization Board of Canada (1st Montreal)