Magnetic field strength of active region filaments C. Kuckein, R. Centeno, V. Martínez Pillet, R. Casini, R. Manso Sainz and T. Shimizu A&A, 501 3 (2009) 1113-1121 Published online: 27 May 2009 DOI: 10.1051/0004-6361/200911800