Amplified radio emission from cosmic ray air showers in thunderstorms S. Buitink, W. D. Apel, T. Asch, F. Badea, L. Bähren, K. Bekk, A. Bercuci, M. Bertaina, P. L. Biermann, J. Blümer et al. (60 more) A&A, 467 2 (2007) 385-394 Published online: 20 February 2007 DOI: 10.1051/0004-6361:20066006