Index of the Troelstra Archive Paul van Ulsen Abstract: Index of the archive of Anne S. Troelstra (born 1939, former professor in pure mathematics and the foundation of mathematics at the university of Amsterdam): summing up of his letters, articles and books from the sixties onwards. The archive is from 2003 a part of the collection of the Rijksarchief Noord-Holland in Haarlem. Keywords: intuitionism, proof theory