In 2004, the Belgian post office issued a special sheet to commemorate the Tintin story “Objectif Lune” and “On A Marché A La Lune”. The stamps featured scenes from the albums, along with two interesting reference documents. One of them is a picture of Hergé with a model the studio constructed in order to maintain a correct perspective in the drawings.
Overall, a very nice issue, which is still widely available on Ebay and other sources.
