The following publications are possibly variants of this publication:
- Okapi at TREC-5Micheline Hancock-Beaulieu, Mike Gatford, Xiangji Huang, Stephen E. Robertson, Steve Walker, P. W. Williams. trec 1996: [doi]
- Okapi at TREC-4Stephen E. Robertson, Steve Walker, Micheline Hancock-Beaulieu, Mike Gatford, A. Payne. trec 1995: [doi]
- Okapi at TREC-2Stephen E. Robertson, Steve Walker, Susan Jones, Micheline Hancock-Beaulieu, Mike Gatford. trec 1993: 21-34 [doi]
- Okapi at TREC-3Stephen E. Robertson, Steve Walker, Susan Jones, Micheline Hancock-Beaulieu, Mike Gatford. trec 1994: 109-126
- Okapi/Keenbow at TREC-8Stephen E. Robertson, Steve Walker. trec 1999: [doi]
- Interactive Okapi at TREC-6Micheline Hancock-Beaulieu, Mike Gatford. trec 1997: 143-167 [doi]
- Interactive Okapi at Sheffield - TREC-8Micheline Hancock-Beaulieu, Helene Fowkes, Nega Alemayehu, Mark Sanderson. trec 1999: [doi]
- Okapi Chinese Text Retrieval Experiments at TREC-6Xiangji Huang, Stephen E. Robertson. trec 1997: 137-142 [doi]
- Okapi at TREC-7: Automatic Ad Hoc, Filtering, VLC and InteractiveStephen E. Robertson, Steve Walker, Micheline Hancock-Beaulieu. trec 1998: 199-210
- Okapi at TREC-6 Automatic ad hoc, VLC, routing, filtering and QSDRSteve Walker, Stephen E. Robertson, Mohand Boughanem, Gareth J. F. Jones, Karen Sparck Jones. trec 1997: 125-136 [doi]
- Experimentation as a way of life: Okapi at TRECStephen E. Robertson, Steve Walker, Micheline Hancock-Beaulieu. ipm, 36(1):95-108, 2000.
- Laboratory experiments with Okapi: participation in the TREC programmeStephen E. Robertson, Steve Walker, Micheline Beaulieu. jd, 53(1):20-34, 1997. [doi]