[1] S2 Cells: A Foundation of Pokemon GO Design | Pokemon GO GamePress () <https://pokemongo.gamepress.gg/s2-cells-foundation-pokemon-go-design>
[2] S2 cells and Pokémon GO | Pokemon GO Hub (Zeroghan著, ) <https://pokemongohub.net/post/wiki/s2-cells-pokemon-go/>
[3] S2 cells and Pokémon GO | Pokemon GO Hub (Zeroghan著, ) <https://pokemongohub.net/post/wiki/s2-cells-pokemon-go/>
[4] S2 Geometry () <http://s2geometry.io/>
[5] google/s2geometry: Computational geometry and spatial indexing on the sphere () <https://github.com/google/s2geometry>
[6] ポケモンGO用のS2セルビューワーを公開しました - Togetter () <https://togetter.com/li/1198900>
[7] 【ポケモンGO】EXレイドの開催地区が検索可能に!?話題のS2セルとは?【ミュウツー】 | ポケモンGO攻略ニュース () <http://pokemongo-news.com/archives/164725>