@article{MABA_1993_7_2_a8,
     author = {G. Kirov and L. Popova},
     title = {A {Generalization} of the {Linear} {Positive} {Operators}},
     journal = {Mathematica balkanica},
     pages = {149},
     publisher = {mathdoc},
     volume = {7},
     number = {2},
     year = {1993},
     url = {http://geodesic.mathdoc.fr/item/MABA_1993_7_2_a8/}
}