Dandia, Anshu, et al. “Synthesis of Fluorine Containing Tetracyclic Ring Systems: 1,2,4-Triazino [3’,4’,3,4] [1,2,4] Triazino [5,6-B] Indole and 1,2-4-Triazino [4’,3’:2,3] [1,2,4] Triazino [5,6-B] Indole ”. Asian Journal of Chemistry, vol. 9, no. 3, Mar. 2010, pp. 501-8, https://asianpubs.org/index.php/ajchem/article/view/23908.