"J. W. Engel Dead; Movie Pioneer, 60. Retired Producer a Founder of Universal, Famous Players and the Metro Company. Discoverer of Valentino. Helped on Bernhardt's First Starring Picture--Made Talkie, 'Hell's Angels'"
April 20, 1943 · pg. 24:2
Moving Picture World (US)
"'Joe' Engel, a Metro Founder, Joins Ranks of Producers"
December 6, 1924 · pg. 509
Moving Picture World (US)
"Course of Film Empire Sways to South; So Declares Treasurer Joseph W. Engel of Metro Following Visit to Florida--Pictures Gaining in Havana"