St. Jerome (recto); Kneeling Male Nude, with His Head and Shoulders Leaning Back (verso) by Juan del Castillo https://www.rawpixel.com/image/14246252/image-cartoon-face-handFree Image from public domain licenseAllegorical Figure of Friendship (recto); Christ on the Cross (verso) by Juan del Castillo https://www.rawpixel.com/image/14247942/image-paper-heart-cartoonFree Image from public domain license