see [[Btrfs]], [https://btrfs.wiki.kernel.org/index.php/Main_Page Btrfs@kernel.org], [https://wiki.archlinux.org/title/Btrfs Btrfs@ARCH-wiki], [https://de.wikipedia.org/wiki/Btrfs Btrfs@wikipedia]
see btrfs@kernel.org, Btrfs@ARC-wiki, Btrfs@wikipedia