@article{MAN_1913__74_158623,
     author = {G.D. Birkhoff},
     title = {A {Theorem} on {Matrices} of {Analytic} {Functions.}},
     journal = {Mathematische Annalen},
     pages = {122--133},
     year = {1913},
     volume = {74},
     url = {http://geodesic.mathdoc.fr/item/MAN_1913__74_158623/}
}