VASARELY (Victor) - BUTOR (Michel). Octal. German translation and Postface by Helmut Scheffel. Munich: Bruckmann, [1972]. - Grand in-folio, 480 x 400. Illustrated black canvas cardboard from the publisher, with printed plastic jacket and white canvas slipcase from the publisher. Original bilingual edition, French and German, printed at 1050 copies and illustrated with 9 large color lithographs by Victor VASARELY (1906-1997), executed on Rives-Couronne vat paper. The text in French is printed in black on grey laid paper, while the German translation is printed in blue on transparent film superimposed on the original text. One of the 150 head copies includes Vasarely's signature at the bottom of all the lithographs, and bears Michel Butor's signature on the title page. Very well preserved copy.