D. B. Nilov, A. V. Kadushkin, N. P. Solov'eva, A. L. Sedov, V. G. Granik, “Interaction of P<sub>2</sub>S<sub>5</sub>–pyridine with enamines. Synthesis and reactions of l,6-trimethylene-5-cyano-2-mercapto-l,3,2-diazaphosphorine-2-thione”, Mendeleev Commun., 6:5 (1996), 191–193