The flare model for X-ray variability of NGC 4258 T. Trześniewski, B. Czerny, V. Karas, T. Pecháček, M. Dovčiak, R. Goosmann and M. Nikołajuk A&A, 530 (2011) A136 Published online: 25 May 2011 DOI: 10.1051/0004-6361/201016369