@article{CMUC_1992__33_4_a15,
     author = {Chen, Xiangdong},
     title = {On binary coproducts of frames},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {699--712},
     publisher = {mathdoc},
     volume = {33},
     number = {4},
     year = {1992},
     mrnumber = {1240192},
     zbl = {0824.54004},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1992__33_4_a15/}
}