T. Guo, M. Liu, J. Jiang, S.-J. Qiu, and Z.-X. Ge, “Synthesis of 7-Azidofurazano[3,4-b]tetrazolopyrazine and Isomer’s Structure in Different Polarity Solvents”, ajc, vol. 25, no. 9, pp. 4979–4982, Aug. 2013.