@article{MAN_1970__188_162048,
     author = {J. KIST and S. LEESTMA},
     title = {Additive {Semigroups} of {Positive} {Real} {Numbers.}},
     journal = {Mathematische Annalen},
     pages = {214--218},
     publisher = {mathdoc},
     volume = {188},
     year = {1970},
     zbl = {0188.05702},
     url = {http://geodesic.mathdoc.fr/item/MAN_1970__188_162048/}
}