Bekar, M., F. Hathout, and Y. Yayli. 2021. “Legendre Curves and the Singularities of Ruled Surfaces Obtained by Using Rotation Minimizing Frame”. Ukrains’kyi Matematychnyi Zhurnal 73 (5), 589 - 601. https://doi.org/10.37863/umzh.v73i5.895.