@article{JRAM_1881__90_148465,
     author = {Emile Picard},
     title = {Sur les \'equations diff\'erentielles lin\'eaires \`a coefficients doublement p\'eriodiques.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {281--302},
     publisher = {mathdoc},
     volume = {90},
     year = {1881},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1881__90_148465/}
}