1. W.C. Roentgen, Sitzungsber.Phys.-Med. Ges. Würzburg 137 (1895) 1; Ann. Phys. Chem. 64 (1898).
2. X-ray telescopes
3. W. Cash, High resolution imaging, in: M. J. L. Turner et al. (Eds.), Leicester X-ray Astronomy Group Special Report, XRA 97/02; pp. 147–153, 1997.
4. G. Schmahl, Röntgenoptik, in: Bergmann-Schäfer, 9th Edition, Walter de gruyter, 1996, pp. 982–1008.
5. N. Rando, M. Perryman A. Peacock, F. Favatam, S-Cam: an imaging spectro-photometer based on superconducting tunnel junctions, ESALAB, 2000/017/SA, 2000, 23 pp. accepted by Experimental Astronomy, February 2000.