diff --git a/assets/js/lib/delta.js b/assets/js/lib/delta.js
index 70ee68071..2051e483a 100644
--- a/assets/js/lib/delta.js
+++ b/assets/js/lib/delta.js
@@ -3,8 +3,10 @@
  *
  * See `Livebook.Delta` for more details.
  *
- * Also see https://github.com/quilljs/delta
- * for a complete implementation of the Delta specification.
+ * An implementation of the full Delta specification is available
+ * in the official quill-delta package (https://github.com/quilljs/delta)
+ * licensed under MIT. Our version is based on that package,
+ * but simplified to match our non rich-text use case.
  */
 export default class Delta {
   constructor(ops = []) {
diff --git a/lib/livebook/delta.ex b/lib/livebook/delta.ex
index 457bfd1d0..e2a413b42 100644
--- a/lib/livebook/delta.ex
+++ b/lib/livebook/delta.ex
@@ -13,8 +13,11 @@ defmodule Livebook.Delta do
   # need to work with plain-text, so we use a subset of the specification
   # with operations listed in `Livebook.Delta.Operation`.
   #
-  # Also see https://hexdocs.pm/text_delta/TextDelta.html
-  # for a complete implementation of the Delta specification.
+  # An implementation of the full Delta specification is available
+  # in the :text_delta package (https://github.com/deltadoc/text_delta)
+  # by Konstantin Kudryashov under the MIT license. This module builds
+  # directly on that package, and is simplified to better fit our
+  # not rich-text use case.
 
   defstruct ops: []