@article{RM_1995_50_1_a13,
     author = {P. I. Topalov},
     title = {The action variable and the {Poincar\'e} {Hamiltonian} in a~neighbourhood of the critical circle},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {216--217},
     publisher = {mathdoc},
     volume = {50},
     number = {1},
     year = {1995},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1995_50_1_a13/}
}