Absolute high- superconducting radiometer with electrical-substitution for X-rays measurements I.A. Khrebtov, A.D. Tkachenko, K.V. Ivanov, A.D. Nikolenko et V.F. Pindyurin J. Phys. IV France, 12 3 (2002) 137-140 DOI: 10.1051/jp420020053