[1] Wilhite, D. A., "Drought: A Global Assessment", Rutledge Press, London and New York, Volume I, 2000.
[2] Heim Jr., "A Review of Twentieth-Century Drought Indices Used in the United States" Bulletin of the American Meteorological Society, 2002, 83 (8), 1149-1166.
[3] Mishra, A. K., Singh, V. P., "Drought Modeling - A Review", Journal of Hydrology, 2011, 403 (1-2), 157-175.
[4] Wilhite, D. A., Glantz, M. H., "Understanding the Drought Phenomenon: The Role of Definitions", Water International, 1985, 10, 111-120.
[5] AMS (American Meteorological Society), "Statement on Meteorological Drought", Bulletin of American Meteorological Society, 2004, 85, 771-773.
[6] Barua, S., Ng, A. W. M., Perera, B. J. C., "Comparative Evaluation of Drought Indices: A Case Study on The Yarra River Catchment in Australia", Journal of Water Resources Planning and Management, 2011, 137 (2), 215-226.
[7] Moreira, E. E., Coelho, C. A., Paulo, A. A., Pereira, L. S., Mexia, J. T., "SPI-based Drought Category Prediction Using Loglinear Models", Journal of Hydrology, 2008, 354, 116-130.
[8] Mishra, A. K., Vijay, P. S., "A Review of Drought Concepts", Journal of Hydrology, 2010, 391, 202-216.
[9] Panu, U. S., Sharma, T. C., "Challenge in Drought Research: Some Perspectives and Future Directions", Hydrological Science Journal, 2002, 47, 19-30.
[10] Guttman, N. B., "Accepting the Standardized Precipitation Index: A Calculation Algorithm", Journal of American Water Resources Management, 1999, 35, 311-322.
[11] Keyantash, J., Dracup, J. A., "The Quantification of Ddrought: An Evaluation of Drought Indices", Bulletin of the American Meteorological Society, 2002, 83 (8), 1167-1180.
[12] Morid, S., Smakhtin, V., Moghaddasi, M., "Comparison of Seven Meteorological Indices for Drought Monitoring in Iran", International Journal of Climatology, 2006, 26, 971-985.
[13] Lokas, A., Vasiliades, L., Dalezios, N. R., "Inter Comparison of Meteorological Drought Indices for Drought Assessment and Monitoring in Greece", 8th International Conference on Environmental Science and Technology Lemons Island, 8-10 September, 2003, pp 484-491.
[14] سبزیپرور، ع.، کاظمی، آ.، "ارزیابی تطبیقی هفت نمایه خشکسالی هواشناسی با استفاده از روش تحلیل خوشهای"، مجله علوم و تکنولوژی محیط زیست، 1389، 12 (1)، 97-111.
[15] خلیقی سیگارودی، ش.، صادقی سنگدهی، ع.، اوسطی، خ.، قویدل رحیمی، ی.، "بررسی نمایههای ارزیابی ترسالی و خشکسالی (SPI,PNPI,Nitzche) (مطالعه موردی استان مازندران)"، فصلنامه علمی - پژوهشی تحقیقات مرتع و بیابان ایران، 1388، 16 (1)، 44-54.
[16] Adeloye A. J., Montaseri M., "Preliminary Streamflow Data Analyses Prior to Water Resources Planning Study", Hydrological Sciences Journal, 2002, 47 (5), 679-692.
[17] Bars, R. L., "Hydrology: An Introduction to Hydrologic Science", Addison-Wesley Publishing Co., New York, USA, 1990.
[18] Kendall M. G., Stuart A., "The Advanced Theory of Statistics", Charles Griffin & Company, London, High Wycombe, 1976. pp 400-401.
[19] McGhee, J. W., "Introductory Statistics", West Publishing Co., New York, USA, 1985.
[20] Vogel, R. M., Kroll, C. N., "Low Flow Frequency Analysis Using Probability Plot Correlation Coefficients", Journal of Water Resources Planning and Management, 1989, 115 (3), 338-357.
[21] Oladipo, E. O., "A Comparative Performance Analysis of Three Meteorological Drought Indices", Journal of Climatology, 1985, 5, 655-664.
[22] Hayes, M. J., Michael, J., "What is Drought? Drought Indices", Climate Impacts Specialist, National Drought Mitigation Center, 2002.
[23] Nitzche, M. H., Silva, B. B., Martinez, A. S., "Indicativo de ano Seco e Chuvoso. Sociedade Brasileira de Agrometeorologia", Londrina-PR, Brazil, 1985, pp 307-314.
[24] Willeke, G., Hosking, J. R. M., Wallis, J. R., Guttman, N. B., "The National Drought Atlas", Institute for Water Resources Report 94-NDs-4, US Army Crops of Engineers, 1994.
[25] Mishra, A. K., Singh, V. P., Desai, V. R., "Drought Characterization: A Probabilistic Approach",
Stochastic Environmental Research and Risk Assessment, 2009, 23 (1), 41-55.
[26] Mckee, T. B., Doesken, N. Y., Kleist, Y., "The Relationship of Drought Frequency and Duration to Time Scales", Preprints, 8th Conference on Applied Climatology, Anaheim, 17-22 January, 1993, pp 179-184.
[27] Edwards, D. C., Mckee, T. B., "Characteristics of 20th Century Drought in the United State at Multiple Time Scales", Atmospheric Science, 1997, 634, 1-30.
[28] Douglas, H., "How to Measure Anything: Finding the Value of Intangibles in Business", John Wiley and Sons, Inc., Hoboken, NJ, 2000, pp 43-47.
[29] Chow, V. T., Maidment, D. R., Mays, L. W., "Applied Hydrology", McGraw-Hill Book Co., New York, 1988.
[30] Salas, J. D., "Analysis and Modeling of Hydrologic Time Series", in handbook of Hydrology, Edited by Maidment, McGrow-Hill book Co., New York, 1993.
[31] McMahon, T. A., Mein, R. G., "River and Reservoir Yield", Water Resources Publications, Littleton, Colorado, 1986.
[32] Valencia, D., Schaake, J. C., "Disaggregation Processes in Stochastic Hydrology", Water Resources Research, 1973, 9 (3), 580-585.
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