@article{ND_2008_4_3_a1,
     author = {V. V. Kozlov},
     title = {Gauss principle and realization of constraints},
     journal = {Russian journal of nonlinear dynamics},
     pages = {281--286},
     publisher = {mathdoc},
     volume = {4},
     number = {3},
     year = {2008},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ND_2008_4_3_a1/}
}