@article{10_1090_S1079_6762_06_00156_9,
     author = {Kruglikov, Boris and Matveev, Vladimir},
     title = {Vanishing of the entropy pseudonorm for certain integrable systems},
     journal = {Electronic research announcements of the American Mathematical Society},
     pages = {19--28},
     publisher = {mathdoc},
     volume = {12},
     year = {2006},
     doi = {10.1090/S1079-6762-06-00156-9},
     url = {http://geodesic.mathdoc.fr/articles/10.1090/S1079-6762-06-00156-9/}
}