@article{VMJ_2017_19_4_a2,
     author = {A. G. Kusraev and S. S. Kutateladze},
     title = {Calculus of tangents and beyond},
     journal = {Vladikavkazskij matemati\v{c}eskij \v{z}urnal},
     pages = {27--34},
     publisher = {mathdoc},
     volume = {19},
     number = {4},
     year = {2017},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/VMJ_2017_19_4_a2/}
}