Karel APPEL (1921-2006) - Boy Jumping on a Blue Hat, 1974. Colour lithograph on wove paper, signed in pencil and justified "EA" (artist's proof). Publisher: Editions Press, San Francisco, 1974. Brown stain in lower right corner, 67 x 87 cm. Color lithograph on wove paper, signed in pencil and justified "EA" (Artist's Proof). Publisher: Editions Press, San Francisco, 1974. Brown stain on the lower right corner, 67 x 87 cm.