@article{AM2_1989__37_2-3_137297,
     author = {Zsolt P\'ales},
     title = {A {Hahn-Banach} theorem for separation of semigroups and its application.},
     journal = {Aequationes mathematicae},
     pages = {141--161},
     publisher = {mathdoc},
     volume = {37},
     number = {2-3},
     year = {1989},
     zbl = {0691.46002},
     url = {http://geodesic.mathdoc.fr/item/AM2_1989__37_2-3_137297/}
}