From Treasures of Disney Animation Art © 1982 Disney
The Modern Mechanix site has a scan of a Popular Science article about Disney’s making of Snow White and the Seven Dwarfs. The cover date is January 1938, which means it was on newsstands in December 1937 to coincide with the release of the movie. [Link here]. The text of the article is provided in addition to the scan, which is available in multiple sizes. Nice touches.