Unveiling the nature of INTEGRAL objects through optical spectroscopy - V. Identification and properties of 21 southern hard X-ray sources
N. Masetti, L. Morelli, E. Palazzi, G. Galaz, L. Bassani, A. Bazzano, A. J. Bird, A. J. Dean, G. L. Israel, R. Landi, A. Malizia, D. Minniti, F. Schiavone, J. B. Stephen, P. Ubertini and R. Walter
