@misc{indiciaef72484ee43ad,
  title = {The travel cost method and the economic value of leisure time},
  author = {Aaron J. Douglas and Richard L. Johnson},
  year = {2004},
  doi = {10.1002/jtr.500},
  url = {https://pubs.usgs.gov/publication/1015185},
  note = {Source identifier: 1015185}
}