1. Y.J. Uemura, et al., Phys. Rev. Lett. 66 (1991) 2665; Nature 352 (1991) 605; Hyperfine Interact. 86 (1994) 615.
2. For a review see: C.G. Kuper, G.D. Whitfied (Eds.), Polarons and Excitons Oliver and Boyd, Edinburgh, 1963, and also A.S. Alexandrov, Europhys. Lett. 56 (2001) 92 (2001);
3. A.S. Alexandrov, N. Mott, High Temperature Superfluids and other Superconductors, Taylor & Francis, London, 1994.
4. The Electron–Phonon Interaction in Metals;Grimvall,1981