Wikipedia:Articles for deletion/Duke Carl Gregor of Mecklenburg
per , multiple independent reviews of multiple works.  Reviews of his books include https://www.jstor.org/stable/41116168https://www.jstor.org/stable/850529https://www.jstor.org/stable/41115482https://www.jstor.org/stable/23230661https://www.jstor.org/stable/23892876https://www.jstor.org/stable/896076https://www.jstor.org/stable/41116958.  Slightly weak only because some of the reviews are a fair ways towards the brief side
— User:Russ, 16:36, 21 August 2020 (UTC)
Stance: keep
Cited policy: WP:NAUTHOR (Wikipedia:Notability)