Mohammed, Khaled M., and Duraid A. Al-Dulaimi. “Synthesis and Characterization of Heterocyclic Seven Membered Rings from 2,3-Pyridine Caroboxylic Anhydride”. Ibn AL-Haitham Journal For Pure and Applied Sciences, vol. 29, no. 2, Mar. 2017, pp. 421-36, https://jih.uobaghdad.edu.iq/index.php/j/article/view/139.