@article{MAN_1904__59_158158,
     author = {Edward Kasner},
     title = {A characteristic property of isothermal systems of curves},
     journal = {Mathematische Annalen},
     pages = {352--354},
     year = {1904},
     volume = {59},
     zbl = {35.0622.03},
     url = {http://geodesic.mathdoc.fr/item/MAN_1904__59_158158/}
}