Tomma JH, AL-Aliawi KML, Ali IT. Synthesis of New Asymmetrical Pyromellitdiimide and Their Amic Acids Containing Heterocyclic Unit. IHJPAS. 2017;27(1):234-246. Accessed March 27, 2025. https://jih.uobaghdad.edu.iq/index.php/j/article/view/382