[1] S. Golian, O. Mazdiyasni, A. AghaKouchak, Trends in meteorological and agricultural droughts in Iran, Theoretical and applied climatology, 119(3-4) (2015) 679-688.
[2] M. Rebetez, H. Mayer, O. Dupont, D. Schindler, K. Gartner, J.P. Kropp, A. Menzel, Heat and drought 2003 in Europe: a climate synthesis, Annals of Forest Science, 63(6) (2006) 569-577.
[3] S.M. Vicente-Serrano, S. Beguería, J.I. López-Moreno, A multiscalar drought index sensitive to global warming: the standardized precipitation evapotranspiration index, Journal of climate, 23(7) (2010) 1696-1718.
[4] S. Tirivarombo, D. Hughes, Regional droughts and food security relationships in the Zambezi River Basin, Physics and Chemistry of the Earth, Parts A/B/C, 36(14-15) (2011) 977-983.
[5] M.K. Lweendo, B. Lu, M. Wang, H. Zhang, W. Xu, Characterization of Droughts in Humid Subtropical Region, Upper Kafue River Basin (Southern Africa), Water, 9(4) (2017) 242.
[6] S. Gurrapu, A. Chipanshi, D. Sauchyn, A. Howard, Comparison of the SPI and SPEI on predicting drought conditions and streamflow in the Canadian prairies, in: Proceedings of the 28th Conference on Hydrology, American Meteorological Society Atlanta, USA, 2014, pp. 2-6.
[7] S.M. Vicente-Serrano, G. Van der Schrier, S. Beguería, C. Azorin-Molina, J.-I. Lopez-Moreno, Contribution of precipitation and reference evapotranspiration to drought indices under different climates, Journal of Hydrology, 526 (2015) 42-54.
[8] S. Tirivarombo, D. Osupile, P. Eliasson, Drought monitoring and analysis: Standardised Precipitation Evapotranspiration Index (SPEI) and Standardised Precipitation Index (SPI), Physics and Chemistry of the Earth, Parts A/B/C, (2018).
[9] S. Beguería, S.M. Vicente Serrano, J.I. López-Moreno, M. Angulo-Martínez, A.M. El Kenawy, The SPEIbase: A new gridded product for the analysis of drought variability and drought impacts, (2010).
[10] L. Labudova, L. Schefczyk, G. Heinemann, The comparison of the SPI and the SPEI using COSMO model data in two selected Slovakian river basins, in: EGU General Assembly Conference Abstracts, 2014.
[11] T. Törnros, L. Menzel, Addressing drought conditions under current and future climates in the Jordan River region, Hydrology and Earth System Sciences, 18(1) (2014) 305-318.
[12] J.H. Stagge, L.M. Tallaksen, L. Gudmundsson, A.F. Van Loon, K. Stahl, Candidate distributions for climatological drought indices (SPI and SPEI), International Journal of Climatology, 35(13) (2015) 4027-4040.
[13] T. Mavromatis, Drought index evaluation for assessing future wheat production in Greece, International Journal of Climatology: A Journal of the Royal Meteorological Society, 27(7) (2007) 911-924.