FIRST SYNTHESIS AND X-RAY CRYSTAL STRUCTURE OF HEXAHYDROBENZO[B]PYRIDO[3,4, 5-DE]-1,6-NAPHTHYRIDINES Article Voskressensky L.G., Borisova T.N., Listratova A., Vorobiev I.V., Aleksandrov G.G., Varlamov A.V. Journal of Heterocyclic Chemistry. HeteroCorporation. Vol. 42. 2005. P. 1207-1210