1. H.H. Andersen, J.F. Ziegler,Hydrogen stopping powers,Pergamon Press, (1977)
2. B. Aschenbach,App. Optics, Vol. 27 (1988), p 1404
3. K. Bhavnani, R. Vancour,Phillips Lab. Scientific Rep., No.9 (1991), PL-TR-91-2296
4. G.F. Bignami et al.,European (X-ray) Photon Imaging Camera,, (1989) proposal submitted to the European Space Agency for the XMM Cornerstone Mission
5. E.J. Daly,ESA Journal, 12 (1988), p229