@article{JRAM_1976__280_151669,
     author = {R. Mennicken and B. Sagraloff},
     title = {St\"orungstheoretische {Untersuchungen} \"uber {Semi-Fredholmpaare} und -operatoren in lokalkonvexen {Vektorr\"aumen.} {I.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {1--36},
     year = {1976},
     volume = {280},
     zbl = {0353.46001},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1976__280_151669/}
}