1. Computational and Structural Chemistry, GlaxoSmithKline Research & Development, Gunnels Wood Road, Stevenage, Hertfordshire SG1 2NY, U.K.
2. Department of Information Studies, University of Sheffield, Regent Court, 211 Portobello Street, Sheffield S1 4DP, U.K.
3. Novartis Institutes for BioMedical Research, CH-4002 Basel, Switzerland
4. Taylor Cheminformatics Software, 54 Sherfield Avenue, Rickmansworth, Herts WD3 1NL, U.K.