Tomma, Jumbad H., Kadhim M. Lazim AL-Aliawi, and Imad T. Ali. 2017. “Synthesis of New Asymmetrical Pyromellitdiimide and Their Amic Acids Containing Heterocyclic Unit”. Ibn AL-Haitham Journal For Pure and Applied Sciences 27 (1): 234-46. https://jih.uobaghdad.edu.iq/index.php/j/article/view/382.