TY  - RPRT
TI  - Map showing construction materials and nonmetallic mineral resources of Nebraska
AU  - Ralph W. Richards
AU  - R. A. Weeks
AU  - D. M. Larrabee
PY  - 1948
DO  - 10.3133/mb15
UR  - https://pubs.usgs.gov/publication/mb15
ID  - mb15
ER  -