@article{SF_1994__48_3_135319,
     author = {H. Sikic},
     title = {Nonlinear perturbations of postive semigroups.},
     journal = {Semigroup forum},
     pages = {273--302},
     publisher = {mathdoc},
     volume = {48},
     number = {3},
     year = {1994},
     zbl = {0835.47024},
     url = {http://geodesic.mathdoc.fr/item/SF_1994__48_3_135319/}
}