@misc{indiciaec84459d92bb7,
  title = {Overlay map of the glacial geology of parts of the Tyngsboro and Westford, Massachusetts, quadrangles},
  author = {Richard H. Jahns and M.E. Willard and W. S. White and L.W. Currier and S.E. White},
  year = {1977},
  doi = {10.3133/ofr77641},
  url = {https://pubs.usgs.gov/publication/ofr77641},
  note = {Source identifier: ofr77641}
}