In 1645 Christina invited Hugo Grotius to become her librarian, but he died on his way in Rostock. That same year she founded "Ordinari Post Tijdender" ("Regular Mail Times"), the oldest currently published newspaper in the world. In 1647 Johann Freinsheim was appointed as her librarian. After the Battle of Prague (1648), where her armies looted Prague Castle, many of the treasures collected by Rudolph II were brought back to Stockholm. Hence Christina acquired for her library a number of valuable illustrated works and rare manuscripts. The inventory drawn up at the time mentions 100 "an allerhand Kunstbüchern" ("a hundred art books of different kinds"), among them two world-famous manuscripts: Codex Gigas and Codex Argenteus.