Le Demon du jeu, Edition Le Tapis Vert, 1939. One of the booklets serving as support for a work of Jan De Cock in the crox-solo (March 1998). He owned a dozen of these booklets. Jan signs 1 copy and offers it to the president of the crox board. The cover also mentions this: LE JEU attirance morbide... La machine est détraquée! VOICI DES PREUVES. 30 francs.