Rotten to the Core, A Zap Jam, Robert Crumb, Rare Poster. Rotten to the Core, A Zap JamCopyright 1989 R. Crumb, S. Clay Wilson, Griffin, Moscoso, Spain, & Gilbert Shelton Tea-Lautrec Litho. Size: 16 x 23 Inches Condition: MINT. Robert Crumb also known as R. Crumb is an American artist, illustrator, and musician recognized for the distinctive style of his drawings and his critical, satirical, subversive view of the American mainstream. Victor Moscoso is an American illustrator and comic book artist, especially noted for his work in the late 1960s as a designer of psychedelic art and concert posters, manyof which were for The Fillmore and Avalon Ballroom. He is also famous as a contributor to underground comix, and he is among the artists who regularly appears in the Zap Comix. Richard Alden Griffin was an American artist and one of the leading designers of psychedelic posters in the 1960s. He was also a contributor to the underground comix movement whose work appeared regularly in Zap Comix. Griffin was closely identified with the Grateful Dead, having designed some of their best known posters and record jackets. He was also known for his work within the surfing subculture, including his comic strip about a surfer named "Murphy".