WASET
    Basri Çelik,  A Hyperbolic Characterization of Projective Klingenberg Planes.   journal   = {International Journal of Mathematical and Computational Sciences}, [online]. World Academy of Science, Engineering and Technology.
    July 2008, vol. 19(7). 429 - 433
    [viewed 08 May 2024]. Available from: https://publications.waset.org/pdf/3890.