@misc{indiciaed97a045d648e,
  title = {Map showing unconsolidated materials, Ludlow quadrangle, Massachusetts},
  author = {G. W. Leo},
  year = {1974},
  doi = {10.3133/mf503c},
  url = {https://pubs.usgs.gov/publication/mf503C},
  note = {Source identifier: mf503C}
}