Greiner, J. High Energy Astrophysics, MPI for Extraterrestrial Physics, Max Planck Society;
Greiner, J., & Richter, G. A. (2015). Optical counterparts of ROSAT X-ray sources in two selected fields at low vs. high Galactic latitudes. Astronomy & Astrophysics, 575: A42, pp. 1-67. doi:10.1051/0004-6361/201322844.