@article{MM2_1990__68_2_155517,
     author = {Jussi V\"ais\"al\"a},
     title = {Quasisymmetry and {Unions.}},
     journal = {Manuscripta mathematica},
     pages = {101--112},
     publisher = {mathdoc},
     volume = {68},
     number = {2},
     year = {1990},
     zbl = {0709.30017},
     url = {http://geodesic.mathdoc.fr/item/MM2_1990__68_2_155517/}
}