diff --git a/doc/node-props.md b/doc/node-props.md
index b44470d196..d457a4c375 100644
--- a/doc/node-props.md
+++ b/doc/node-props.md
@@ -1,5 +1,5 @@
 # Properties of nodes
-These are properties babel stores in AST node objects for internal use, as opposed to properties that are part of the AST spec (ESTree at the time of this writing).
+These are properties babel stores in AST node objects for internal use, as opposed to properties that are part of the AST spec ([ESTree](https://github.com/estree/estree) at the time of this writing).
 
 ## `_blockHoist`
 `node._blockHoist != null` triggers the [block-hoist transformer](/src/babel/transformation/transformers/internal/block-hoist.js). Value should be `true` or an integer in the range `0..3`. `true` is equivalent to `2`. The value indicates whether the node should be hoisted and to what degree. See the source code for more detailed information.