1. Adnan, S., 2009: Agro-climatic Classification of Pakistan. Master dissertation, COMSATS Institute of Information Technology, Islamabad, Pakistan. [Accessed 29 October, 2014] [Available online at https://www.researchgate.net/publication/261700354-Agroclimatic-Classification-of-Pakistan].
2. Adnan, S., and A. H. Khan, 2009: Effective rainfall for irrigated agriculture plains of Pakistan. Pakistan J. Meteor., 6, 61–72.
3. Asrari, E., M. Masoudi, and S. S. Hakimi, 2012: GIS overlay analysis for hazard assessment of drought in Iran using Standardized Precipitation Index (SPI). J. Ecol. Field Bio., 35, 323–329.
4. Becker, A., P. Finger, A. Meyer-Christoffer, et al., 2013: A description of the global land-surface precipitation data products of the Global Precipitation Climatology Centre with sample applications including centennial (trend) analysis from 1901 to present. Earth System Science Data, 5, 71–99.
5. Cancelliere, A., A. Ancarani, and G. Rossi, 1998: Distribuzioni di probabilità delle caratteristiche di siccità. Atti del XXVI Conv. di Idr. e Costr. Idrauliche, Catania, Italy, 9–12.