Multiline Zeeman signatures through line addition M. Semel, J. C. Ramírez Vélez, M. J. Martínez González, A. Asensio Ramos, M. J. Stift, A. López Ariste and F. Leone A&A, 504 3 (2009) 1003-1009 Published online: 22 July 2009 DOI: 10.1051/0004-6361/200810428