@article{MS2_1998__81_2_167435,
     author = {M.J. Tomkinson},
     title = {Groups as the union of proper subgroups.},
     journal = {Mathematica Scandinavica},
     pages = {191--198},
     publisher = {mathdoc},
     volume = {81},
     number = {2},
     year = {1998},
     zbl = {0905.20014},
     url = {http://geodesic.mathdoc.fr/item/MS2_1998__81_2_167435/}
}