Firestore

https://firebase.flutter.dev/docs/firestore/usage/
https://firebase.google.com/docs/firestore/best-practices?hl=ja
https://qiita.com/shiz/items/5f4c8ae19083ccdd46b2
https://qiita.com/subaru44k/items/a88e638333b8d5cc29f2
https://zenn.dev/mamushi/articles/a5e6c9f71e6ea4
https://gist.github.com/sosmii/8e426cf0986a8a914dd61766b73cf5d8
https://qiita.com/smiler5617/items/8dcf720f5477a5f4b7d7
https://qiita.com/kabochapo/items/1ef39942ac1206c38b2d
https://tenderfeel.xsrv.jp/javascript/4980/
https://zenn.dev/eitches/articles/2021-0130-firestore-reference-snapshot

Firestore Securityrule

https://tech-blog.sgr-ksmt.org/2018/12/11/194022/
https://qiita.com/sgr-ksmt/items/1a731fdadf06119d35fc
https://zenn.dev/kosukesaigusa/articles/efc2528898954d95a6ae
https://zenn.dev/k2wanko/articles/3007acaafce03db58989
https://mintaku-blog.net/storage-securityrule/