Wikipedia:Articles for deletion/Waldemar Heckel
Two of his books are highly cited, which is probably enough for  C1.  And there are several reviews of his books now in the article, which looks like a pass of 
— User:Russ, 17:00, 23 March 2020 (UTC)
Stance: keep
Cited policy: WP:NPROF||WP:NAUTHOR (Wikipedia:Notability)