The volumes, which were previously owned by the Swedish royal family, were stolen from Sweden’s National Library by Anders Burius, the former head of its manuscript department. Burius was responsible for the theft of at least 56 items from the National Library between 1995 and 2004.
The returned items are a 19th-century illustrated text of the Mississippi River and a 17th-century French book on the Louisiana territory. Both had been bought and sold by an American book dealer who had no idea the items had been stolen. When informed of the theft by the FBI, he bought the books back at his own expense so they could be returned to Sweden.
Source: New York Times