“Synthesis Of New Asymmetrical Pyromellitdiimides Derived From Pyromellitic Dianhydride”. Ibn AL-Haitham Journal For Pure and Applied Sciences 25, no. 3 (May 8, 2017): 284–293. Accessed April 27, 2024. https://jih.uobaghdad.edu.iq/index.php/j/article/view/595.