@article{10_2298_FIL2214893E,
     author = {I El Ouali and M Ech-Cherif El Kettani and M Karmouni},
     title = {Quasi-Fredholm spectrum for operator matrices},
     journal = {Filomat},
     pages = {4893 },
     year = {2022},
     volume = {36},
     number = {14},
     doi = {10.2298/FIL2214893E},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.2298/FIL2214893E/}
}