A comparison of borer, ripper, and conventional mining products in Illinois No. 6 seam coal.  by R.L  Schmidt, W.H. Engelmann, and R.R. Fumanti.
Contributors: Engelmann, W.H.; Fumanti, R.R.
Publisher: U.S.  Dept. of the Interior
Place of publication: Washington
Language: eng
Number of pages: 18
Notes: 11