@misc{indiciae81a1e5e8c784,
  title = {Visitor impact assessment and monitoring systems: Evolution and current development},
  author = {Y.-F. Leung and J. L. Marion and D.N. Cole},
  year = {2002},
  url = {https://pubs.usgs.gov/publication/5211190},
  note = {Source identifier: 5211190}
}