Astrometry of International Celestial Reference Frame sources using the second US Naval Observatory CCD astrograph catalog - Assafin, M; Monken Gomes, P. T; Silva Neto, D. N; Andrei, A. H; Martins, R. Vieira; Camargo, J. I. B; Teixeira, Ramachrisna; Benevides-Soares, Paulo (Astronomical Journal, 2005)