Electromagnetically induced two-photon transparency in rubidium atoms D. Wang, J. Y. Gao, J. H. Xu, G. C. La Rocca and F. Bassani Europhys. Lett., 54 4 (2001) 456-460 Published online: 01 December 2003 DOI: 10.1209/epl/i2001-00267-5