Diamond drilling and diamond bit investigation.
Part 1,
Drilling tests in uniform granite /
by Leonard Obert [and others].

APA Citation

Long, A., Chayes, F., Gabriel, A., Agnew, W. G., Obert, L. (1947). Diamond drilling and diamond bit investigation. [Washington, D.C.]: U.S. Dept. of the Interior, Bureau of Mines.

MLA Citation

Obert, L, et al.. Diamond Drilling And Diamond Bit Investigation. [Washington, D.C.]: U.S. Dept. of the Interior, Bureau of Mines, 1947.

Warning: These citations may not always be complete (especially for serials).