LONDON (Reuters) – An archive showing the development of J.R.R. Tolkien’s classic fantasy “The Lord of the Rings” is expected to fetch up to 35,000 pounds ($50,940) when it goes under the hammer next month.

The archive, which was compiled by Tolkien’s friend George Sayer and includes proof copies, first editions and letters by the author, will be shown for the first time on Thursday, auction house Christie’s said in a statement.

“The Lord of the Rings” about Hobbits, trolls, elves and wizards has sold an estimated 100 million copies worldwide. It was first published in three parts in 1954-55.

The first film in the $300 million trilogy, “The Fellowship of the Ring,” starring Ian McKellen, Cate Blanchett and Christopher Lee, is set to open in December and critics predict it will be a blockbuster.