EL-ASKARY HI, EL-OLEMY MM, SALAMA MM and AMER MH, 2014. Development and validation of a high-performance liquid chromatography method for standardization of the bioactive ethyl acetate fraction of Alstonia scholaris (Linn.) R. Br. growing in Egypt. Zeitschrift fur Naturforschung. C, Journal of biosciences. 68(9-10), 376-83