@article{CMUC_1970_11_4_a1,
     author = {Pultr, Ale\v{s}},
     title = {Tensor products in the category of graphs},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {619--639},
     year = {1970},
     volume = {11},
     number = {4},
     mrnumber = {0387373},
     zbl = {0214.51102},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1970_11_4_a1/}
}