The on-sale date is from the publication date recorded in the Catalog of Copyright Entries, Part 2, Periodicals, 1941, New Series, Vol. 36, No. 4.
Harry Graves is not listed by Jerry Bails in the Who's Who, nor is the feature.
Bill Black states that Jerry Bails' "Collector's Guide: The First Heroic Age" from 1969 and Howard Keltner's "Index to Golden Age Comics Books" from 1976 both list the feature.