References to cronopios in Cortázar's work occur in 20 short sketches that make up the last section of "Historias de Cronopios y de Famas" as well as in his "collage books," "La vuelta al día en ochenta mundos" and "Ultimo Round," which were collected in a French edition he considered definitive. Some literary critics consider Cortazar's cronopios stories as lesser works compared to other of the author's novels and short stories. Others have looked for hidden metaphysical meanings in these stories or for a universal taxonomy of human beings. Cortázar himself described these stories as a sort of "game" and asserted that writing them gave him great joy.