Olga V. Kharchenko,  Optical Parametric Oscillators Lidar Sounding of Trace Atmospheric Gases in the 3-4 ┬Ám Spectral Range .   journal   = {International Journal of Geological and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology.
    May 2016, vol. 115(7). 721 - 726
    [viewed 05 August 2020]. Available from: https://publications.waset.org/pdf/10004739.