Non-thermal radio emission from O-type stars - II. HD 167971 R. Blomme, M. De Becker, M. C. Runacres, S. Van Loo and D. Y. A. Setia Gunawan A&A, 464 2 (2007) 701-708 Published online: 02 January 2007 DOI: 10.1051/0004-6361:20054602