@article{Plane2005,
author = {Plane, D.A. and Henrie, C.J. and Perry, M.J.},
title= {Migration up and down the urban hierarchy and across the life course},
year = {2005},
doi = {10.1073/pnas.0507312102},
journal = {PNAS},
volume = {102},
number = {43},
pages = {15313--15318},
}