Nurmakhanov Нурмаханов Б.Н., and Karazhanov A.A. Каражанов А.А. 2022. “Geometric Design of the Surface of an Underground Working Using (2-2)-Digit Transformation Г2”. Рroblems of Engineering and Professional Education 2 (2):8. https://doi.org/10.32523/2220-685X-2010-2-2-8.