@article{AIHPA_1967__6_4_267_0,
     author = {Testard, D.},
     title = {Alg\`ebre de covariance},
     journal = {Annales de l'institut Henri Poincar\'e. Section A, Physique Th\'eorique},
     pages = {267--297},
     publisher = {Gauthier-Villars},
     volume = {6},
     number = {4},
     year = {1967},
     mrnumber = {218907},
     zbl = {0152.46306},
     language = {fr},
     url = {http://www.numdam.org/item/AIHPA_1967__6_4_267_0/}
}