@article{Ludo2012,
author = {Ludo, P.},
title= {Gravity and spatial structure: The case of interstate migration in Mexico},
year = {2012},
doi = {10.1111/j.1467-9787.2012.00770.x},
journal = {Journal of Regional Sciences},
volume = {52},
number = {5},
pages = {819--856},
}