N. H. Abd Raof and  H. Abu Hassan and  S.K. Mohd Bakhori and  S. S. Ng and  Z. Hassan,  Structural and Optical Properties ofInxAlyGa1-x-yN Quaternary Alloys.   journal   = {International Journal of Electronics and Communication Engineering}, [online]. World Academy of Science, Engineering and Technology.
    July 2009, vol. 31(7). 1448 - 1451
    [viewed 19 February 2020]. Available from: https://publications.waset.org/pdf/10639.