P. A. Roussos, G. Dimitriou, and A. E. Voloudakis, “Short communication. N-(2-chloro-4-pyridyl)-N-phenylurea(4-CPPU) enhances in vitro direct shoot organogenesis of Citrus aurantium L. epicotyl segments compared to other commonly used cytokinins”, Span. j. agric. res., vol. 9, no. 2, pp. 504-509, May 2011.