1. American Meteorological Society (2004) Statement on meteorological drought. Bull Am Meteorol Soc 85:771–773
2. Blaikie P, Cannon T, Davis I, Wisner B (1994) At risk: natural hazards, people’s vulnerability, and disasters. Routledge, London
3. Bonaccorso B, Cancelliere A, Rossi G (2003) An analytical formulation of return period of drought severity. Stoch Environ Res Risk Assess 17:157–174
4. Calow R, Robins N, Macdonald A, Nicol A (1999) Planning for groundwater drought in Africa. In: Proceedings of the international conference on integrated drought management: lessons for sub-Saharan Africa. IHP-V, Technical Documents in Hydrology, 35:255–270
5. Cancelliere A, Salas JD (2010) Drought probabilities and return period for annual streamflows series. J Hydrol 391:77–89