@article{JGG_2024_28_1_JGG_2024_28_1_a1,
     author = {H. Katsuura },
     title = {In and {Ex} {Spheres} of a {Tetrahedron}},
     journal = {Journal for geometry and graphics},
     pages = {19--27},
     publisher = {mathdoc},
     volume = {28},
     number = {1},
     year = {2024},
     url = {http://geodesic.mathdoc.fr/item/JGG_2024_28_1_JGG_2024_28_1_a1/}
}