Probalistic Learning Approaches for Indexing and Retrieval with the TREC-2 Collection. - Norbert Fuhr; Ulrich Pfeifer; C. Bremkamp; Michael Pollmann (TREC, 1993)

Routing and Ad-hoc Retrieval with the TREC-3 Collection in a Distributed Loosely Federated Environment. - Nikolaus Walczuch; Norbert Fuhr; Michael Pollmann; Birgit Sievers (TREC, 1994)