The Index Volumes E 23 m and E 23 n list all polycyclic chemical compounds in the supplementary volumes of Houben-Weyl E 1 - E 21, including carbocyclic, heterocyclic and organometallic polycyclic systems. It is based principally on organic (i.e., carbon-containing) compounds. The reaction products are indexed, however, reagents and starting materials are not. In contrast to the other compound indexes in Houben-Weyl, this index is based exclusively on chemical formulas and there are no full systematic names given. On a given ring system with definite numbering, the substituents are shown as chemical symbols or abbreviations, i.e., carbon chains are cited in a line. These substituents are listed in descending order in accordance with the Cahn-Ingold-Prelog (CIP) system. The preparative procedures are given in bold type.