@article{TSG_1982-1983__1__A3_0,
     author = {Colin de Verdi\`ere, Yves},
     title = {Sur les longueurs des trajectoires p\'eriodiques d'un billard},
     journal = {S\'eminaire de th\'eorie spectrale et g\'eom\'etrie},
     note = {talk:3},
     pages = {1--18},
     publisher = {Institut Fourier},
     address = {Grenoble},
     volume = {1},
     year = {1982-1983},
     zbl = {1126.37307},
     language = {fr},
     url = {http://www.numdam.org/item/TSG_1982-1983__1__A3_0/}
}