@article{JRAM_1984__348_152606,
     author = {Shen Chun-li},
     title = {A generalization of the {Schwarz-Ahlfors} lemma fo the theory of harmonic maps.},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {23--33},
     publisher = {mathdoc},
     volume = {348},
     year = {1984},
     zbl = {0519.58026},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1984__348_152606/}
}