Simultaneous radio and X-ray observations of the low-mass X-ray binary GX 13+1 J. Homan, R. Wijnands, M. P. Rupen, R. Fender, R. M. Hjellming, T. di Salvo and M. van der Klis A&A, 418 1 (2004) 255-263 Published online: 02 April 2004 DOI: 10.1051/0004-6361:20034258