diff --git a/docs/xpath.rst b/docs/xpath.rst
index a338485f2e017cd24968ecd089176c9bbf1d835e..2a4d4849a87b2f27aa9df3cb84da0a4f6c7684f2 100644
--- a/docs/xpath.rst
+++ b/docs/xpath.rst
@@ -27,10 +27,12 @@ XPath Abstract Syntax Tree
    :synopsis: Abstract syntax tree for XPath expressions
 
 The :mod:`.xpathast` module defines classes that allow for building
-`abstract syntax trees` (AST) for XPath 1.0 expressions with
+`abstract syntax trees`__ (AST) for XPath 1.0 expressions with
 extensions introduced by YANG 1.1. Only the following class is
 intended to be public:
 
+__ https://en.wikipedia.org/wiki/Abstract_syntax_tree
+
 * :class:`Expr`: XPath 1.0 expression with YANG 1.0 extensions.
 
 The module also defines the following exception: