BibTex, you need to define a new citation command (`\acite`) and a `\bibalias`[1] command that allows you to cite the same entry with two different keys (see [here](https://tex.stackexchange.com/questions/37233/having-several-keys-refer-to-the-same-bibliography-entry) for how to de...
19EinAbsatzwirdgeformt99 20Kopfzeilenleichtgemacht101 21Querverweise—interneundexterne105 21.1FlexibleQuerverweise105 21.2QuerverweiseaufexterneDokumente107 22WennL A T E XSiewo¨rtlichnehmensoll109 22.1Dasalltt-Paket109 22.2Dasverbatim-Paket109 ...