Cadwalader Ringgold:
AMRA v2 #57 June 1973 - cover artist Roy G. Krenkel "study for Saber-Tooth-Cat scene"
Cadwalader Ringgold:
AMRA v2 #58 January 1973 - cover artist Roy G. Krenkel "Jurassic Scene"
Cadwalader Ringgold:
AMRA v2 #51 November 1969 - cover artist Roy G. Krenkel "Almuric"
Cadwalader Ringgold:
AMRA v2 #54 April 1971 - cover artist Roy G. Krenkel "Cathage near the Old North gate"
Cadwalader Ringgold:
Edgar Rice Burroughs - Out of Time's Abyss - cover artist Roy G. Krenkel, Jr.
Cadwalader Ringgold:
Edgar Rice Burroughs - The Eternal Savage - cover artist Roy G. Krenkel, Jr.
Cadwalader Ringgold:
Tanar of Pellucidar - E.R. Burroughs - cover artist Roy G. Krenkel