1. GINGA observations of three X-ray-luminous early-type galaxies - NGC 4472, NGC 4636, and NGC 3998
2. The fourth UHURU catalog of X-ray sources.
3. Green D. A. 2004, A Catalog of Galactic Supernova Remnants, 2004 January version (Cambridge, UK: Mullard Radio Astronomy Observatory) 1
4. Kondo H. 1988, Master’s thesis, The University of Tokyo (in Japanese)
5. Koyama K. Kondo H. Makino F. Nagase F. Takano S. Tawara Y. Turner M. J. L. Warwick R. S. 1989, PASJ, 41, 483