1. Nomenclature of fused and bridged fused ring systems (IUPAC Recommendations 1998)
2. Nomenclature of Organic Chemistry IUPAC Recommendations and Preferred Names 2013 Chapter P-2 H. A. Favre W. H. Powell Royal Society of Chemistry: Cambridge England 2014.
3. We contacted the eighteen commercial resources by email in Feb. 2020 for purchase of indolo[3 2-b]carbazole and got ten replies. Seven of them replied that it was out of stock; and three of them provided quotation on the basis of customized synthesis. However upon our further request these three commercial resources replied that they were not able to provide any information about the appearance and characterization data of indolo[3 2-b]carbazole because they had not synthesized it before.
4. Über zweistufige Redoxsysteme, XXIII1) Kondensierte Stickstoffheterocyclen