The imprint of cosmological hydrogen recombination lines on the power spectrum of the CMB J. A. Rubiño-Martín, C. Hernández-Monteagudo and R. A. Sunyaev A&A, 438 2 (2005) 461-473 Published online: 08 July 2005 DOI: 10.1051/0004-6361:20052939