X-ray and optical observations of BL Lac objects: 3C 66A (B0219+428) and ON 325 (B1215+303)M. Perri, E. Massaro, P. Giommi, M. Capalbi, R. Nesci, G. Tagliaferri, G. Ghisellini, M. Ravasio and H. R. MillerA&A, 407 2 (2003) 453-460DOI: https://doi.org/10.1051/0004-6361:20030915
