1. Anderson P.W., Halperin B.I., Varma C.M. (1792) . The Philos. Mag. 25, 19
2. W. A. Phillips, J. Low Temp. Phys., 7(3–4), 351f́b360 (1972).
3. L. Risegari et al., 8th International Conference of Astroparticle, Particle and Space Physics, Detectors and Medical Physics Applications ICATPP, World Scientific, pp. 603–607 (2003).
4. Pohl R.O., Liu X., Thompson E. (2002) . Rev. Mod. Phys. 74(4):9911013
5. Benes M. et al. (2005) . J. Therm. Anal. Calorim. 82(3):761–768