@article{PIM_1973_N_S_15_29_a18,
     author = {H. P. Tan},
     title = {Countable {And} {Uncountable} {Covers}},
     journal = {Publications de l'Institut Math\'ematique},
     pages = {151 },
     publisher = {mathdoc},
     volume = {_N_S_15},
     number = {29},
     year = {1973},
     url = {http://geodesic.mathdoc.fr/item/PIM_1973_N_S_15_29_a18/}
}