E. G. Cavalcante Junior, A. D. Oliveira, B. M. de Almeida, and J. Espínola Sobrinho, “Methods of estimation of reference crop evapotranspiration for the conditions of northeastern semi-arid, Brazil”, Semina: Ciênc. Agrár., vol. 32, no. 4Sup1, pp. 1699–1708, Dec. 2011.