@article{Marshall2009,
author = {Marshall, J.D. and Brauer, M. and Frank, L.D.},
title= {Healthy neighborhoods: Walkability and air pollution},
year = {2009},
doi = {10.1289/ehp.0900595},
journal = {Environmental Health Perspectives},
volume = {117},
number = {11},
pages = {1752--1759},
}