Analysis of the long-term polarization behaviour of BL LacV. A. Hagen-Thorn, E. G. Larionova, S. G. Jorstad, C.-I. Björnsson and V. M. LarionovA&A, 385 1 (2002) 55-61DOI: https://doi.org/10.1051/0004-6361:20020145