@article{10_4153_CJM_1998_007_7,
     author = {M\'edan, Christine},
     title = {On {Critical} {Level} {Sets} of {Some} two {Degrees} of {Freedom} {Integrable} {Hamiltonian} {Systems}},
     journal = {Canadian journal of mathematics},
     pages = {134--151},
     year = {1998},
     volume = {50},
     number = {1},
     doi = {10.4153/CJM-1998-007-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1998-007-7/}
}