The INTEGRAL long monitoring of persistent ultra compact X-ray bursters M. Fiocchi, A. Bazzano, P. Ubertini, A. J. Bird, L. Natalucci and V. Sguera A&A, 492 2 (2008) 557-563 Published online: 30 October 2008 DOI: 10.1051/0004-6361:200809715