1. Climatic Atlas of Clouds over Land and Ocean http://www.atmos.washington.edu/CloudMap [accessed 26.03.12].
2. Variations in cloud cover and cloud types over the ocean from surface observations 1954-2008;Eastman;Journal of Climate,2011
3. Advances in understanding clouds from ISCCP;Rossow;Bulletin of the American Meteorological Society,,1999
4. Surface based cloud climatology webpage:http://www.atmos.washington.edu/CloudMap/.
5. Global distribution of total cloud cover and cloud type amounts over land;Warren,1986