@article{10_4153_CJM_1991_020_7,
     author = {Krantz, Steven G. and Parks, Harold R.},
     title = {On the {Vector} {Sum} of {Two} {Convex} {Sets} in {Space}},
     journal = {Canadian journal of mathematics},
     pages = {347--355},
     year = {1991},
     volume = {43},
     number = {2},
     doi = {10.4153/CJM-1991-020-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1991-020-7/}
}