@misc{Richardson_G._B._(1872-1949)_Bulletin,
 author={Richardson, G. B. (1872-1949)},
 howpublished={online},
 publisher={Government Printing Office.},
 language={eng},
 type={journal},
 title={Bulletin 873. Geology and mineral resources of the Butler and Zelienople quadrangles, Pennsylvania},
 keywords={geology, mineralogy, journals, United States of America},
}