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The first version of his treatise, "Secreta fidelium crucis" (Secrets for True Crusaders), was written between 1306 and 1307 and presented to Pope Clement V. Over the years he continued to revise and expand his manuscript, adding a history of the Holy Lands to 1307 and a geography of the Levant. In 1321 Sanuto presented his new version to Pope John XXII and a French translation was sent to King Charles IV of France. The "Liber Secretorum" was copied numerous times and lavishly illustrated versions were sent to influential people throughout Europe. At least eleven copies are known to survive.