@article{MM2_1987__59_155241,
     author = {Fumio Sakai},
     title = {On polarized normal surfaces.},
     journal = {Manuscripta mathematica},
     pages = {109--128},
     publisher = {mathdoc},
     volume = {59},
     year = {1987},
     zbl = {0635.14016},
     url = {http://geodesic.mathdoc.fr/item/MM2_1987__59_155241/}
}