  Since its launch on October 2002, the INTEGRAL satellite has revolutionized
our knowledge of the hard X-ray sky thanks to its unprecedented imaging
capabilities and source detection positional accuracy above 20 keV.
Nevertheless, many of the newly-detected sources in the INTEGRAL sky surveys
are of unknown nature. The combined use of available information at longer
wavelengths (mainly soft X-rays and radio) and of optical spectroscopy on the
putative counterparts of these new hard X-ray objects allows pinpointing their
exact nature. Continuing our long-standing program running since 2004, here we
report the classification, through optical spectroscopy, of 19 more
unidentified or poorly studied high-energy sources detected with the IBIS
instrument onboard INTEGRAL.
