books.google.com - The observational evidence for the existence of black holes has grown significantly over recent decades. Stellar-mass black holes are detected as X-ray sources in binary systems, while supermassive black holes, with masses more than a million times the mass of the Sun, lurk in the nuclei of galaxies....http://books.google.com/books/about/Black_Holes_in_Binaries_and_Galactic_Nuc.html?id=whZ-AYBH6zYC&utm_source=gb-gplus-shareBlack Holes in Binaries and Galactic Nuclei: Diagnostics, Demography and Formation
