@article{SF_1975__10_134124,
     author = {M. Friedberg},
     title = {Semirings on cones.},
     journal = {Semigroup forum},
     pages = {329--350},
     publisher = {mathdoc},
     volume = {10},
     year = {1975},
     zbl = {0299.22003},
     url = {http://geodesic.mathdoc.fr/item/SF_1975__10_134124/}
}