diff --git a/include/boost/unordered/concurrent_flat_map.hpp b/include/boost/unordered/concurrent_flat_map.hpp
index 585b4a87..e0abf6a7 100644
--- a/include/boost/unordered/concurrent_flat_map.hpp
+++ b/include/boost/unordered/concurrent_flat_map.hpp
@@ -8,10 +8,6 @@
  * See https://www.boost.org/libs/unordered for library home page.
  */
 
-/* Reference:
- * https://github.com/joaquintides/concurrent_hashmap_api#proposed-synopsis
- */
-
 #ifndef BOOST_UNORDERED_CONCURRENT_FLAT_MAP_HPP
 #define BOOST_UNORDERED_CONCURRENT_FLAT_MAP_HPP
 
diff --git a/include/boost/unordered/concurrent_flat_map_fwd.hpp b/include/boost/unordered/concurrent_flat_map_fwd.hpp
index a4d76cc0..3a39c7a7 100644
--- a/include/boost/unordered/concurrent_flat_map_fwd.hpp
+++ b/include/boost/unordered/concurrent_flat_map_fwd.hpp
@@ -8,10 +8,6 @@
  * See https://www.boost.org/libs/unordered for library home page.
  */
 
-/* Reference:
- * https://github.com/joaquintides/concurrent_hashmap_api#proposed-synopsis
- */
-
 #ifndef BOOST_UNORDERED_CONCURRENT_FLAT_MAP_FWD_HPP
 #define BOOST_UNORDERED_CONCURRENT_FLAT_MAP_FWD_HPP