@book{Sen1995,
author = {Sen, A. and Smith, T.E.},
title= {Gravity models of spatial interaction behavior},
year = {1995},
doi = {10.1007/978-3-642-79880-1},
URL = {https://doi.org/doi:10.1007/978-3-642-79880-1},
address = {Berlin},
publisher = {Springer},
}