diff --git a/2021/zfs-snapshots.md b/2021/zfs-snapshots.md
index 31a3246..83bc070 100644
--- a/2021/zfs-snapshots.md
+++ b/2021/zfs-snapshots.md
@@ -21,4 +21,5 @@ zfs set snapdir=visible zroot/data/syncthing
 ```
 
 See:
-* https://github.com/j-keck/zfs-snap-diff
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+* https://github.com/j-keck/zfs-snap-diff
+* https://j-keck.github.io/zsd/
\ No newline at end of file