Quasi-periodicities of BL Lacertae objects A. Sandrinelli, S. Covino, A. Treves, A. M. Holgado, A. Sesana, E. Lindfors and V. F. Ramazani A&A, 615 (2018) A118 Published online: 24 July 2018 DOI: 10.1051/0004-6361/201732550