@misc{indiciae7724008b0d0e,
  title = {Aeromagnetic map of the Royalston quadrangle, Worcester and Franklin Counties, Massachusetts, and Cheshire County, New Hampshire},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1971},
  doi = {10.3133/gp727},
  url = {https://pubs.usgs.gov/publication/gp727},
  note = {Source identifier: gp727}
}