@article{SM_2018_209_9_a4,
     author = {A. A. Oshemkov and M. A. Tuzhilin},
     title = {Integrable perturbations of saddle singularities of rank~0 of integrable {Hamiltonian} systems},
     journal = {Sbornik. Mathematics},
     pages = {1351--1375},
     publisher = {mathdoc},
     volume = {209},
     number = {9},
     year = {2018},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_2018_209_9_a4/}
}