@phdthesis{THESE_1923__41__1_0,
     author = {Lagrange, Ren\'e},
     title = {Sur le calcul diff\'erentiel absolu},
     series = {Th\`eses de l'entre-deux-guerres},
     type = {Doctorat d'\'Etat},
     number = {41},
     year = {1923},
     mrnumber = {3532910},
     language = {fr},
     url = {http://www.numdam.org/item/THESE_1923__41__1_0}
}

Lagrange, René. Sur le calcul différentiel absolu. Thèses de l'entre-deux-guerres, no. 41 (1923), 80 p. http://www.numdam.org/item/THESE_1923__41__1_0/