@article{VMUMM_1989_6_a9,
     author = {V. Yu. Ovsienko},
     title = {A {Lagrangian} {Schwarzian} derivative},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {42--45},
     publisher = {mathdoc},
     number = {6},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_1989_6_a9/}
}