@article{CHEB_2023_24_5_a10,
     author = {S. Yu. Soloviev},
     title = {About cotangent},
     journal = {\v{C}eby\v{s}evskij sbornik},
     pages = {167--179},
     publisher = {mathdoc},
     volume = {24},
     number = {5},
     year = {2023},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/CHEB_2023_24_5_a10/}
}