@article{MABA_2003_17_3-4_a5,
     author = {S. Hakkaev and R. Nickolov and Zh. Zhelev},
     title = {Subscalarity of a {Class} of {Triangular} {Operator} {Matricies}},
     journal = {Mathematica balkanica},
     pages = {231},
     publisher = {mathdoc},
     volume = {17},
     number = {3-4},
     year = {2003},
     url = {http://geodesic.mathdoc.fr/item/MABA_2003_17_3-4_a5/}
}