@article{10_4064_ap_71_1_31_38,
     author = {Jolanta Olko},
     title = {Concave iteration semigroups of linear set-valued functions},
     journal = {Annales Polonici Mathematici},
     pages = {31--38},
     publisher = {mathdoc},
     volume = {71},
     number = {1},
     year = {1999},
     doi = {10.4064/ap-71-1-31-38},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap-71-1-31-38/}
}