Magnetic twist and writhe of active regions - On the origin of deformed flux tubesM. C. López Fuentes, P. Démoulin, C. H. Mandrini, A. A. Pevtsov and L. van Driel-GesztelyiA&A, 397 1 (2003) 305-318DOI: https://doi.org/10.1051/0004-6361:20021487
