4. Documenta : internationale ausstellung 27. Juni bis 6. Oktober 1968 Kassel

The first volume has a foreword by Dr. Karl Branner, and then chapters by art historians such as Max Imdahl, Arnold Bode, Jean Leering, Jurgen Harten, Janni Muller-Hauck, and others. The second volume is devoted to a worldwide exhibition of the works of Albers and Bury, Chillida and Dekkers, Dine and Dubuffet, Warhol, Hockney and multitudinous others