A quasi-periodic modulation of the radio light curve of the blazar PKS B0048-097 M. Kadler, P. A. Hughes, E. Ros, M. F. Aller and H. D. Aller A&A, 456 2 (2006) L1-L4 Published online: 31 August 2006 DOI: 10.1051/0004-6361:200600026