Spectroscopy of high-energy BL Lacertae objects with X-shooter on the VLT S. Pita, P. Goldoni, C. Boisson, J.-P. Lenain, M. Punch, L. Gérard, F. Hammer, L. Kaper and H. Sol A&A, 565 (2014) A12 Published online: 23 April 2014 DOI: 10.1051/0004-6361/201323071