Kavianpour, Mohammadreza, Mohammadreza Seyedabadi, Saber Moazami, and Omid Aminoroayaie Yamini. 2020. “Copula Based Spatial Analysis of Drought Return Period in Southwest of Iran”. Periodica Polytechnica Civil Engineering 64 (4):1051-63. https://doi.org/10.3311/PPci.16301.