Search for "indolo[3,2-b]carbazole" in Full Text gives 3 result(s) in Beilstein Journal of Organic Chemistry.
Beilstein J. Org. Chem. 2017, 13, 1396–1406, doi:10.3762/bjoc.13.136
Beilstein J. Org. Chem. 2016, 12, 2490–2494, doi:10.3762/bjoc.12.243
Beilstein J. Org. Chem. 2010, 6, No. 12, doi:10.3762/bjoc.6.12