@article{BSMF_1933__61__209_0,
     author = {Haag, Jules},
     title = {Sur le calcul de la dur\'ee des petites oscillations en fonction de leur amplitude},
     journal = {Bulletin de la Soci\'et\'e Math\'ematique de France},
     pages = {209--212},
     publisher = {Soci\'et\'e math\'ematique de France},
     volume = {61},
     year = {1933},
     doi = {10.24033/bsmf.1205},
     zbl = {0008.05603},
     language = {fr},
     url = {http://www.numdam.org/articles/10.24033/bsmf.1205/}
}