The first detection of radio recombination lines at cosmological distancesK. L. Emig, P. Salas, F. de Gasperin, J. B. R. Oonk, M. C. Toribio, H. J. A. Röttgering and A. G. G. M. TielensA&A, 622 (2019) A7DOI: https://doi.org/10.1051/0004-6361/201834052
