Hussein, S. . T., Ali, E. . T., Ali, K. . F., & Tomma, J. . H. (2017). Evidence Supports The Formation Of Isoimides Derived From Pyromellitic Dianhydride. Ibn AL-Haitham Journal For Pure and Applied Sciences, 26(1), 241-249. https://jih.uobaghdad.edu.iq/index.php/j/article/view/530