@article{BSMF_1914__42__91_1,
     author = {Donder, Th. De},
     title = {Sur les invariants int\'egraux de l'optique},
     journal = {Bulletin de la Soci\'et\'e Math\'ematique de France},
     pages = {91--95},
     publisher = {Soci\'et\'e math\'ematique de France},
     volume = {42},
     year = {1914},
     doi = {10.24033/bsmf.941},
     language = {fr},
     url = {http://www.numdam.org/articles/10.24033/bsmf.941/}
}