@article{10_37236_9475,
     author = {Colin Defant and James Propp},
     title = {Quantifying noninvertibility in discrete dynamical systems},
     journal = {The electronic journal of combinatorics},
     year = {2020},
     volume = {27},
     number = {3},
     doi = {10.37236/9475},
     zbl = {1475.37045},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/9475/}
}