@article{MZM_1978_24_4_a9,
     author = {Ya. B. Pesin},
     title = {Equations for the entropy of a geodesic flow on a compact {Riemannian} manifold without conjugate points},
     journal = {Matemati\v{c}eskie zametki},
     pages = {553--570},
     publisher = {mathdoc},
     volume = {24},
     number = {4},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1978_24_4_a9/}
}