Filtering by: Contributor Frey, Hildebrand, 1940- Remove constraint Contributor: Frey, Hildebrand, 1940- Creator Heckmann, Ralf Remove constraint Creator: Heckmann, Ralf Date 2007 Remove constraint Date: 2007 Resource type http://purl.org/coar/resource_type/c_db06 Remove constraint Resource type: http://purl.org/coar/resource_type/c_db06