Shortened footnote and citation:
{{sfn | Schäfer | 2017 | p=}}
* {{cite book | last=Schäfer | first=Erich | title=Lebenslanges Lernen | publisher=Springer | publication-place=Berlin; [Heidelberg] | date=2017-05-12 | isbn=978-3-662-50421-5 | language=de}}
Named reference:
<ref name="r913">{{cite book | last=Schäfer | first=Erich | title=Lebenslanges Lernen | publisher=Springer | publication-place=Berlin; [Heidelberg] | date=2017-05-12 | isbn=978-3-662-50421-5 | language=de | page=}}</ref>