Deletion of Robert Brown Gardner

Comment: The Wilkens reference makes a strong case for his notability (fitting into #C1). Backing this up, his books are also well cited on Google scholar
Stance: keep
Cited policy: Wikipedia:Notability (WP:PROF)

Comment: A retrospective in a mainstream mathematical publication clinches 
Stance: keep
Cited policy: Wikipedia:Notability (WP:PROF)