@article{JGG_2018_22_2_JGG_2018_22_2_a5,
     author = {K. Morita},
     title = {Theorems on {Two} {Tetrahedrons} {Intersecting} a {Sphere}},
     journal = {Journal for geometry and graphics},
     pages = {219--227},
     year = {2018},
     volume = {22},
     number = {2},
     url = {http://geodesic.mathdoc.fr/item/JGG_2018_22_2_JGG_2018_22_2_a5/}
}