Observation of narrow fluorescence from doubly driven four-level atoms at room temperatureU. K. Khan, J. Sebastian, N. Kamaraju, A. Narayanan, R. Srinivasan and H. RamachandranEurophys. Lett., 67 1 (2004) 35-41DOI: https://doi.org/10.1209/epl/i2003-10274-0