@article{JRAM_1987__377_152926,
     author = {Jos\'e Felipe Voloch and Karl-Otto St\"ohr},
     title = {A formula for the {Cartier} operator on plane algebraic curves.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {49--64},
     publisher = {mathdoc},
     volume = {377},
     year = {1987},
     zbl = {0605.14023},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1987__377_152926/}
}