Abdollahi, J., Arzani, H., Baghestani, N. and Askarshahi, F.S.M. (2007). Rainfall and ground water table change influencing the seidletzia rosmarinous growth and development at the Chah-Afzal Ardakan, Journal of Range and Desert Reseach, 13(2), 74-81.
 Abdollahi, J., Arzani, H. and Naderi, H. (2011). Climatic factors affecting on production of forage Noudushan rangelands in Yazd Province, Journal of rangland, 5(1), 45-56.
 Akbarzadeh, M., Moghadam, M.R., Jalili, A., Jafari, M. and Arzani, H. (2007). Effect of precipitation on cover and production of rangeland plants in Polour, Journal of the Natural Resources, 60(1), 307-322.
 Alizadeh, A. (2013). Applied principle of hydrology, imam Reza University press, Mashhad.
 Andales, A., Derner, J., Ahuja, L. and Hart, R. (2006). Strategic and Tactical Precipitation of forage Production in North Mixed-Grass Prairie, Rangland Ecology & Management, 59(6), 576-584.
 Azarakhshi, M., Mahdavi, M. and Arzani, H. (2009). Determining the best drought indices in arid and semi-arid regions of the seen product of rangeland plants (Case Study: Qom, Markazi
and Ilam). Ph.D. thesis. 203PP.
 Baghestani Maybodi, N. and Zare, M.T. (2007). Investigation of relationship between annual precipitation and yield in steppic of Poosht-kooh region of Yazd province. Journal of Pajouhesh & Sazandegi, 75, 103-107.
 Bates, J.D., Svejcar, T., Miller, R.F. and Angell, R.A. (2006). The effects of precipitation timing on sagebrush steppe vegetation, Journal of Arid Environments, 67, 670-697.
 Benie, G., Kabore, S., Goita, K. and Courel, M. (2005). Remote sensing-based spatio-temporal modeling to predict biomass in Sahelian grazing ecosystem, Journal of Ecological Modelling, 184, 341-354.
 Borg, D. (2009). An Application of Drought Indices in Malta, Case Study, European Water, 26, 38-25.
 Elagib, N. and Elhag, M. (2011). Major climate indicators of ongoing drought Sudan, Journal of Hydrology, 409, 612-625.
 Evans, S., Byrne, K., K.Lauenroth, W.C. and Burke, I. (2011). Defining the limit to resistant in drought-tolerant grassland: long-term severe drought significantly reduces the dominant species and increases ruderals, Journal of Ecology, 99, 1500-1507.
 Ehsani, A., Arzani, H., Farahpour, M., Ahmadi, H., Jafari, H., Jalili, A., Mirdavoudi, H.R., Abasi, H.R. and Azimi, M.S. (2007). The effect of climatic conditions on range forage production in steppe rangelands, Akhtarabad of Saveh, Journal of Range and Desert Research, 14(2), 260-249.
 Elshorbagy, A., Corzo, G., Srinivasulu, S. and Solomatine, D. (2009). Experimental investigation of the predictive capabilities of soft computing techniques in hydrology, Centre for Advanced Numerical Simulation (CANSIM), Department of Civil & Geological Engineering, University of Saskatchewan, Saskatoon, SK, CANADA. 49 p.
 Forrest, A.S. and hyder, S.N. (1985). Estimating herbage production on semi-arid ranges in the intermountain region, Journal of Range Management, 15, 88-93.
 Hein, L. (2006). The impacts of grazing and rainfall variability on the dynamics of a sahelian rangeland, Journal of Arid Environments, 64, 488-504.
 Heitschmidt, R.K., Klement, K.D. and HaferKamp, M.R. (2005). Interactive Effects of drought and Grazing Northern Great Plains Rangelands, Rangeland Ecology & Management, 58, 19-11.
 Jankju, M. (2008). Individual Performances and the Interaction between Arid Land Plants Affected by the Growth Season Water Pulses, Arid Land Research and Management, 22, 123-133.
 Khumalo, G. and Holechek, J. (2005). Relationship between Chihuahan Desert Perennial Grass Product and Precipitation, Rangeland Ecology & Management, 58, 239-246.
 Liu, Y., Pan, Q., Zheng, S., Bai, Y. and Han, X. (2012). Intra-seasonal precipitation amount and pattern differentially affect primary production of two dominant species Inner Mongolia grassland, Acta Oecologia, 44, 2-10.
 McKee, T.B., Doesken, N.J. and Kleist, J. (1993). The Relationship of Drought Frequency and Duration to Time Scales, Paper Presented at 8th Conference on Applied Climatology, American Meteorological Society, Anaheim, CA.
 Mirjalili, A.B. and moosaei sanjareei, M. (2009). The effect of climate on range forage production in tangelaybid, Yazd, Second Regional Conference on Natural Resources and the Environment, Arsanjan.
 Mishra, A.K. and Singh, V.P. (2010). A review of drought concepts, Journal of Hydrology, 391, 202-216.
 Moghaddam, M., mohammadi, A. and Aghaei, M. (2010). Introduction to multivariate statistical methods, Paryvar press, Azarbaygan sharghi.
 Mosaedi, A. and Ghabaei Sough, M. (2012). Modification of Standardized Precipitation Index (SPI) Based on Relative Probability Distribution Function, Journal of Water and Soil, 25(5), 1206-1216.
 Munkhtsetseg, E., Kimura, R., Wang, J. and Shinoda, M. (2007). Pasture yield response to precipitation and high temperature in Mongolia, Journal of Arid Environments, 70, 94-110.
 Sharifan, H., Ghahreman, B., Alizadeh, A. and Mir.latifi, M. (2006). Comparison of the different methods of estimated Reference Evapotranspiration (Compound and Temperature) with standard method and analysis of aridity effects, Journal of Agric. Sci.Natur.Resour, 13(1), 19-30.
 Smart, A., Dunn, B. and Gates, R. (2005). Historical Weather Patterns: A Guide for Drought Planning, Rangelands, 27(2), 10-12.
 Smart, A., Dunn, B., Johnson, P., Xu, L., and Gates, R. (2007). Using weather data to explain herbage yield on three great plain plant communities, Rangeland Ecology & Management, 60(2), 146-153.
 Schwinning, S., Starr, B.I. and Ehleringer, J.R. (2005). Summer and winter drought in cold desert ecosystem (Colorado Plateau) part II: effects on plant carbon assimilation and growth, Journal of Arid Environments, 61, 61-78.
 Torell, L.A., McDaniel, K.C. and Koren, V. (2011). Estimating grass yield on blue grama range from seasonal rainfall and soil moisture measurements, Rangeland Ecology & Management, 64(1), 56-66.
 Tsakiris, G. and Vangelis, H. (2004). Towards a drought watch system based on spatial SPI, Journal of Water Resources Management, 18, 1-12.