Shortened footnote and citation:
{{sfn | Gysi | Sonneborn | 2021 | p=}}
* {{cite book | last=Gysi | first=Gregor | last2=Sonneborn | first2=Martin | title=Gysi vs. Sonneborn | publisher=Aufbau Digital | date=2021-05-17 | isbn=978-3-8412-2675-4 | language=de}}
Named reference:
<ref name="d811">{{cite book | last=Gysi | first=Gregor | last2=Sonneborn | first2=Martin | title=Gysi vs. Sonneborn | publisher=Aufbau Digital | date=2021-05-17 | isbn=978-3-8412-2675-4 | language=de | page=}}</ref>