@misc{indiciaee7109413bb4f,
  title = {The Portage Lake Volcanics (middle Keweenawan) on Isle Royale, Michigan},
  author = {N.K. Huber},
  year = {1973},
  doi = {10.3133/pp754c},
  url = {https://pubs.usgs.gov/publication/pp754C},
  note = {Source identifier: pp754C}
}