@article{SM_1998_189_1_a2,
     author = {E. I. Galakhov and A. L. Skubachevskii},
     title = {On non-negative contractive semigroups with non-local conditions},
     journal = {Sbornik. Mathematics},
     pages = {43--74},
     year = {1998},
     volume = {189},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1998_189_1_a2/}
}