@misc{indiciae8f291b9300d3,
  title = {Map showing construction materials and nonmetallic mineral resources of Montana},
  author = {M. M. Knechtel and R.P. Bryson and P.S. Clabaugh and E.C. Fischer and E.L. Fox and M. H. Krieger and D. M. Larrabee and A. F. Shride and I. G. Sohn and R. A. Weeks},
  year = {1948},
  doi = {10.3133/mb11},
  url = {https://pubs.usgs.gov/publication/mb11},
  note = {Source identifier: mb11}
}