@article{10_4153_CMB_1983_077_8,
     author = {Horton, J. D.},
     title = {Sets with {No} {Empty} {Convex} {7-Gons}},
     journal = {Canadian mathematical bulletin},
     pages = {482--484},
     year = {1983},
     volume = {26},
     number = {4},
     doi = {10.4153/CMB-1983-077-8},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1983-077-8/}
}