diff --git a/doc/src/sgml/protocol.sgml b/doc/src/sgml/protocol.sgml
index 4899bacda7..5793936b42 100644
--- a/doc/src/sgml/protocol.sgml
+++ b/doc/src/sgml/protocol.sgml
@@ -2069,8 +2069,9 @@ The commands accepted in replication mode are:
      </para>
 
      <para>
-      WAL data is sent as a series of CopyData messages.  (This allows
-      other information to be intermixed; in particular the server can send
+      WAL data is sent as a series of CopyData messages
+      (See <xref linkend="protocol-message-types"/> and <xref linkend="protocol-message-formats"/>).
+      (This allows other information to be intermixed; in particular the server can send
       an ErrorResponse message if it encounters a failure after beginning
       to stream.)  The payload of each CopyData message from server to the
       client contains a message of one of the following formats: