00881nam#a2200277zcb4500 990000000200203331 AT-OBV 20230310193044.0 tu 920706|1992####|||###########|||#|#eng#c AC00465769 (AT-OBV)AC00465769 AC00465769 (Aleph)000000020ACC01 (DE-599)OBVAC00465769 TUW ger rakwb eng XD-US MacDonald, L. G. aut Frictional ignition of natural gas-air mixtures by alternative coal-cutter bit shank materials by L. Garner McDonald Washington, DC 1992 14 S. Ill., graph. Darst. Report of investigations / United States Department of the Interior, Bureau of Mines 9417 Literaturverz. S. 9 - 10 (AT-OBV)AC00073533 9417 McDonald, L. G.