@article{MZM_2011_89_2_a1,
     author = {M. Yu. Balakhnev},
     title = {First-Order {Differential} {Substitutions} for {Equations} {Integrable} on~$\mathbb S^n$},
     journal = {Matemati\v{c}eskie zametki},
     pages = {178--189},
     publisher = {mathdoc},
     volume = {89},
     number = {2},
     year = {2011},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_2011_89_2_a1/}
}