diff --git a/docs/pages/api.rst b/docs/pages/api.rst
index b91191d9b..0e2a6e76e 100644
--- a/docs/pages/api.rst
+++ b/docs/pages/api.rst
@@ -1,7 +1,7 @@
 API
 ===
 
-static constructors
+Static constructors
 -------------------
 
 empty
diff --git a/docs/pages/usage.rst b/docs/pages/usage.rst
index 05726e572..ad63119a7 100644
--- a/docs/pages/usage.rst
+++ b/docs/pages/usage.rst
@@ -343,3 +343,6 @@ transform any input (`iterable`) into a regular array.
 The final Collection class implements by default all the interfaces available.
 
 Use it like it is or create your own object by using the same procedure as shown here.
+
+.. _Base Collection class: https://github.com/loophp/collection/blob/master/src/Base.php
+.. _Operation interface: https://github.com/loophp/collection/blob/master/src/Contract/Operation.php
\ No newline at end of file