Synthesis of Dibenzo[c,h][1,6]naphthyridine, [2]Benzopyrano[4,3-c]quinoline and Benzo[i]phenanthridine Analogues of the Quaternary Benzo[c]phenanthridines - Hutton, Susan M; Mackay, Simon Paul; Meth-Cohn, Otto (Synthesis, 2000)