@misc{indiciae5dd7c921688a,
  title = {Tree rings : timekeepers of the past},
  author = {Richard L. Phipps and J. McGowan},
  year = {1989},
  doi = {10.3133/7000101},
  url = {https://pubs.usgs.gov/publication/7000101},
  note = {Source identifier: 7000101}
}