De Sède authored more than 20 books and contributed articles to various magazines, sometimes using the pseudonyms "Pumaz", "Allard", "Gillot" and "Simon". He is best known for his 1967 book "L'Or de Rennes, ou La Vie insolite de Bérenger Saunière, curé de Rennes-le-Château" ("The Gold of Rennes, or The Strange Life of Bérenger Saunière, Priest of Rennes-le-Château"), published as a paperback in 1968 entitled "Le Trésor Maudit de Rennes-le-Château" ("The Accursed Treasure of Rennes-le-Château"). A revised and updated version entitled "Signé: Rose+Croix" was published in 1977.