@article{MAN_1977__229_163019,
     author = {Philip B. Downum},
     title = {Cyclic {Extensions} of {Banach} {Algebras.}},
     journal = {Mathematische Annalen},
     pages = {233--236},
     publisher = {mathdoc},
     volume = {229},
     year = {1977},
     zbl = {0338.32010},
     url = {http://geodesic.mathdoc.fr/item/MAN_1977__229_163019/}
}