El asunto Tornasol
"The Calculus Affair" marked a return to the single volume format which was to persist for the rest of "The Adventures of Tintin". The volume started its publication in "Tintin" magazine in December 1954. Before working on the book, Hergé would make sketches in pencil; subsequently he would work over the drawings and text in ink. With the development of his own Studios Hergé, he selected the best sketch from a number of versions and traced it onto the page he was creating.