.beta.-D-Ribofuranoside, (5,6-dimethyl-6H-pyrido[3,4-b]carbazol-11-yl)methyl .beta.-D-Ribofuranoside, (5,6-dimethyl-6H-pyrido[4,3-b]carbazol-11-yl)methyl 89651-51-4 NSC360319