1. G. Binnig and H. Rohrer; Helv. Phys. Acta, 55, 726 (1982)
2. C. Julian Chen, Introduction to Scanning Tunneling Microscopy, Oxford Series in Optical and Imaging Sciences, Oxford Univ. Press, New York USA, (1993)
3. G. Binnig, C.F. Quate and C. Gerber; Phys. Rev. Lett. 56, 930 (1986)
4. F. O. Goodman and N. Garcia, Phys. Rev. B43, 4728, (1991)
5. Yu. S. Barash and V.L. Ginzburg; Usp. Fiz. Nauk 116, 5 (1975) (Soviet Phys. Usp. 18, 305 (1975); ibid 143,345 (1984) (ibid 27, 467 (1984)