The diverse X-ray properties of four truly isolated elliptical galaxies: NGC 2954, NGC 6172, NGC 7052, and NGC 7785E. Memola, G. Trinchieri, A. Wolter, P. Focardi and B. KelmA&A, 497 2 (2009) 359-370DOI: https://doi.org/10.1051/0004-6361/200810801