1. Kamerlingh Onnes, H.: Further experiments with liquid helium. On the change of the electrical resistance of pure metal at very low temperature. Leiden Commun. 122b, (1911)
2. Barnard B., Caplin A.D.: ‘Simple’ behaviour of the low temperature electrical resistivity of silver?. Commun. Phys. 2, 223–227 (1977)
3. Petit A.T., Dulong P.L.: Sur quelques points importans de la theorie de la chaleur. Ann. Chim. Phys. 10, 395–413 (1819)
4. Barin, I.: Thermochemical Data of Pure Substances. VCH Verlag (1989)
5. Einstein A.: Planck’s theory of radiation and the theory of specific heat. Ann. Physik 22, 180–190 (1906)