X-ray spectral evolution of TeV BL Lacertae objects: eleven years of observations with BeppoSAX, XMM-Newton and Swift satellitesF. Massaro, A. Tramacere, A. Cavaliere, M. Perri and P. GiommiA&A, 478 2 (2008) 395-401DOI: https://doi.org/10.1051/0004-6361:20078639