Holocaust museum
Holocaust museumIsrael news photo: Flash 90

A rare book from Nazi Germany marked with the word “Secret!” was mysteriously dropped off at the LaGrange Park Public Library in Chicago.

The book titled, “1938-1941: Vier Jahre, Hermann Göring-Werke,” was discovered in the library's drop box bin, and may have been discarded had it not landed on the desk of Ursula Stanek, the library’s circulation services director.

Stanek, who grew up in Germany, became aware of the book’s historical significance just prior to travelling to Washington, D.C, where she and her daughter visited the United States Holocaust Memorial Museum.

Stanek delivered the book to the museum in May, after learning that it only had a reprint of the book from the 1990s, not an original.

“It’s a great mystery,” library director Dixie Conkis said, according to The Chicago-Sun Times. “We had the book in our possession for a while not knowing quite what to do with it, but felt that because it was marked ‘secret’ it was probably a rather important book.”

The book details the Nazis’ pride at developing an industrial complex powered by state-owned steel mills in Germany during World War II, The Times reported.

The book also had an envelope with a return address for Paul Pleiger, tried at Nuremberg and sentenced to 15 years in prison for his role in managing Nazi factories.

”It’s nice we were able to find a proper home for such a rare book,” Conkis said. “We received a very nice letter from the Holocaust museum. They were just thrilled to have it.”