NASA - National Aeronautics and Space Administration

Foster, M. J., S. A. Ackerman, K. Bedka, R. A. Frey, L. Di Girolamo, Andrew Heidinger, S. Sun-Mack, B. C. Maddux, W. P. Menzel, P. Minnis, M. Stengel, and G. Zhao (2016), State of the Climate: Cloudiness, Bull. Am. Meteor. Soc., 97, S17-S18.