1,2:6,7-Dibenzophenanthrene 2,3-Benzochrysene 2,3:7,8-Dibenzophenanthrene 214-17-5 3,4-Benzotetracene 3,4-Benzotetraphene 3,4-Benztetraphene Benzo[b]chrysene Benzo[c]tetraphene Dibenzo-2,3,7,8-phenanthrene NSC89274