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@article{MS2_1990__66_1_167106, author = {Jan Boman}, title = {The sum of two plane convex {C...} sets is not always {C...}}, journal = {Mathematica Scandinavica}, pages = {216--224}, publisher = {mathdoc}, volume = {66}, number = {1}, year = {1990}, zbl = {0739.52003}, url = {http://geodesic.mathdoc.fr/item/MS2_1990__66_1_167106/} }
Jan Boman. The sum of two plane convex C... sets is not always C.... Mathematica Scandinavica, Tome 66 (1990) no. 1, pp. 216-224. http://geodesic.mathdoc.fr/item/MS2_1990__66_1_167106/