NASA - National Aeronautics and Space Administration

White, M. A., K. M. de Beurs, K. Didan, D. W. Inouye, A. D. Richardson, O. P. Jensen, J. O'Keefe, G. Zhang, R. Nemani, W. J. D. van Leeuwen, J. F. Brown, A. de Wit, M. Schaepman, X. Lin, M. Dettinger, A. S. Bailey, J. Kimball, M. D. Schwartz, D. D. Baldocchi, J. T. Lee, and W. K. Lauenroth (2009), Intercomparison, interpretation, and assessment of spring phenology in North America estimated from remote sensing for 1982 to 2006, Global Change Biology, doi:10.1111/j.1365-2486.2009.01910.