A. I. Alajtal and  H. G. M. Edwards and  M. A. Elbagermi ,  Vibratinal Spectroscopic Identification of  Beta-Carotene in Usnic Acid and PAHs as a Potential Martian Analogue.   journal   = {International Journal of Bioengineering and Life Sciences}, [online]. World Academy of Science, Engineering and Technology.
    January 2014, vol. 85(1). 50 - 53
    [viewed 25 April 2024]. Available from: https://publications.waset.org/pdf/9997244.