@article{ND_2021_17_4_a1,
     author = {A. Ligeza and H. Zoladek},
     title = {Qualitative {Analysis} of {Some} {Libration} {Points} in the
},
     journal = {Russian journal of nonlinear dynamics},
     pages = {369--390},
     publisher = {mathdoc},
     volume = {17},
     number = {4},
     year = {2021},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ND_2021_17_4_a1/}
}