@article{GDZPPN002360527, title = {The sum of two plane convex C... sets is not always C...}, journal = {Mathematica Scandinavica}, volume = {67}, year = {1990}, pages = {216-224}, zbl = {0739.52003}, url = {http://dml.mathdoc.fr/item/GDZPPN002360527} }
Boman, Jan. The sum of two plane convex C... sets is not always C.... Mathematica Scandinavica, Tome 67 (1990) pp. 216-224. http://gdmltest.u-ga.fr/item/GDZPPN002360527/