Fotsing Tetsing, Hans, Cyriaque Atindogbé, and Ferdinand Nkageu. 2022. “Normalized Null Hypersurfaces in the Lorentz-Minkowski Space Satisfying $L_r X =U X +b$”. Tamkang Journal of Mathematics 54 (4):353-78. https://doi.org/10.5556/j.tkjm.54.2023.4851.