E.El. Habba, N. G. Abdel Aziz, A.M.Z. Sarhan, A. M. S. Arafa, and N. M. Youssef. 2016. “Effect of Putrescine and Growing Media on Vegetative Growth and Chemical Constituents of Populus Euramericana Plants”. Journal of Innovations in Pharmaceutical and Biological Sciences 3 (1):61-73. https://jipbs.com/index.php/journal/article/view/114.