Absence of linear polarization in Hα emission of solar flares M. Bianda, A. O. Benz, J. O. Stenflo, G. Küveler and R. Ramelli A&A, 434 3 (2005) 1183-1189 Published online: 18 April 2005 DOI: 10.1051/0004-6361:20041654