Zhang, L., Jacob, D. J., Knipping, E. M., Kumar, N., Munger, J. W., Carouge, C. C., van Donkelaar, A., Wang, Y., Chen, D. (2012). Nitrogen deposition to the United States: distribution, sources, and processes, Atmospheric Chemistry and Physics, 12, 4539-4554, 10.5194/acp-12-4539-2012