@article{MS2_1969__25_166113,
     author = {J. Barback},
     title = {Extensions to {Regressive} {Isols.}},
     journal = {Mathematica Scandinavica},
     pages = {159--177},
     publisher = {mathdoc},
     volume = {25},
     year = {1969},
     zbl = {0212.33002},
     url = {http://geodesic.mathdoc.fr/item/MS2_1969__25_166113/}
}