Soft X-ray characterisation of the long-term properties of supergiant fast X-ray transients P. Romano, L. Ducci, V. Mangano, P. Esposito, E. Bozzo and S. Vercellone A&A, 568 (2014) A55 Published online: 14 August 2014 DOI: 10.1051/0004-6361/201423867