Elementary coal-mining :
Kerr, George L.,
Elementary coal-mining : Designed to meet the requirements of students attending classes on coal-mining, and of miners and others engaged in practical work / By George l. kerr - 225 páginas
Minas de carbón
TN802 / K47
Elementary coal-mining : Designed to meet the requirements of students attending classes on coal-mining, and of miners and others engaged in practical work / By George l. kerr - 225 páginas
Minas de carbón
TN802 / K47