TY  - RPRT
TI  - Modelling the evolution of human trail systems.
AU  - D Helbing
AU  - J Keltsch
AU  - P Molnár
PY  - 1997
DO  - 10.1038/40353
UR  - https://pubmed.ncbi.nlm.nih.gov/9214501/
ID  - 9214501
ER  -