@article{MM2_1978__25_154555,
     author = {Ernst Albrecht},
     title = {On two questions of {I.} {Colojoara} and {C.} {Foias.}},
     journal = {Manuscripta mathematica},
     pages = {1--16},
     year = {1978},
     volume = {25},
     zbl = {0407.47017},
     url = {http://geodesic.mathdoc.fr/item/MM2_1978__25_154555/}
}