@article{MAN_1972__199_162311,
     author = {R.B. jr. Warfield},
     title = {Exchange {Rings} and {Decompositions} of {Modules.}},
     journal = {Mathematische Annalen},
     pages = {31--36},
     publisher = {mathdoc},
     volume = {199},
     year = {1972},
     zbl = {0228.16012},
     url = {http://geodesic.mathdoc.fr/item/MAN_1972__199_162311/}
}