24 year monitoring of extragalactic sources at 22 and 37 GHz H. Teräsranta, S. Wiren, P. Koivisto, V. Saarinen and T. Hovatta A&A, 440 1 (2005) 409-410 Published online: 19 August 2005 DOI: 10.1051/0004-6361:20053356