Gierlinski, Marek, Zdziarski, Andrzej A., Done, Chris, Johnson, W. Neil, Ebisawa, Ken, Ueda, Yoshihiro, Haardt, Francesco, Phlips, Bernard F., "Simultaneous X-ray and gamma-ray observations of CYG X-1 in the hard state by GINGA and OSSE", Monthly Notices of the Royal Astronomical Society, 1997