Hand, J. L., Copeland, S. A., McDade, C. E., Day, D. E., Moore, C. T., Dillner, A. M., Pitchford, M. L., Indresand, H., Schichtel, B. A., Malm, W. C., Watson, J. G. (2011). Spatial and seasonal patterns and temporal variability of haze and its constituents in the United States, IMPROVE Report V, Cooperative Institute for Research in the Atmosphere