Casgliadau Arlein
Amgueddfa Cymru
Chwilio Uwch
National Federation of Iron & Steel Manuf., report
Typed in black ink on cream paper. 14 pages stapled together. Title: 'Methods of Concentration of Minnesota Iron Ores Investigated by the Minnesota School of Mines'. Dated 1st January 1932.
Nid yw sylwadau ar gael ar hyn o bryd. Ymddiheuriadau am yr anghyfleustra.