Hand, J. L., Schichtel, B. A., Malm, W. C., Pitchford, M. L., Frank, N. H. (2014). Spatial and seasonal patterns in urban influence on regional concentrations of speciated aerosols across the United States, J. Geophys. Res.: Atmos., 119 (22), 12832-12839, DOI: 10.1002/2014JD022328