Books by O. V. Simpson:
Books in the extended shelves:
![[X-Info]](https://onlinebooks.library.upenn.edu/infouc.gif)
Simpson, O. V.: Emergency escapeways from coal mines (U.S. Dept. of the Interior, Bureau of Mines, 1948), also by R. T. Artz (page images at HathiTrust)- Simpson, O. V.: Fire fighting facilities at four Pennsylvania bituminous-coal mines (U.S. Dept. of the Interior, Bureau of Mines, 1949), also by G. W. Grove and United States Bureau of Mines (page images at HathiTrust)
Find more by O. V. Simpson at your library, or elsewhere.