diff --git a/mps/manual/source/pool/awl.rst b/mps/manual/source/pool/awl.rst
index 43e16e73415..870e0980b3c 100644
--- a/mps/manual/source/pool/awl.rst
+++ b/mps/manual/source/pool/awl.rst
@@ -2,7 +2,7 @@
 
     `<https://info.ravenbrook.com/project/mps/master/manual/wiki/pool_classes.html>`_
     `<https://info.ravenbrook.com/project/mps/master/design/poolawl/>`_
-
+    `<http://info.ravenbrook.com/mail/2003/03/17/13-51-24/0.txt>`_
 
 .. _pool-awl:
 
diff --git a/mps/manual/source/topic/message.rst b/mps/manual/source/topic/message.rst
index a9740cf9c24..219c7cedafa 100644
--- a/mps/manual/source/topic/message.rst
+++ b/mps/manual/source/topic/message.rst
@@ -1,19 +1,23 @@
 .. Sources:
 
     `<https://info.ravenbrook.com/project/mps/master/design/message/>`_
+    `<https://info.ravenbrook.com/mail/2005/04/05/13-33-11/0.txt>`_
 
 .. _topic-message:
 
 Messages
 ========
 
-*Messages* are the mechanism by which the MPS communicates with the
-:term:`client program`. The MPS normally runs :term:`asynchronously
-<asynchronous garbage collector>` with respect to the client program,
-so messages are implemented via a :term:`message queue` attached to
-each :term:`arena`.
+The MPS sometimes needs to communicate with the :term:`client program`
+about events which occur :term:`asynchronously <asynchronous garbage
+collector>`, and so information cannot be returned as function call
+results.
 
-The client program must enable each other message type that they are
+*Messages* are the mechanism for this asynchronous communication,
+implemented in the form of a :term:`message queue` attached to each
+:term:`arena`.
+
+The client program must enable each message type that they are
 prepared to handle, by calling :c:func:`mps_message_type_enable`. Then
 it must poll the message queue at regular intervals when it is
 convenient to do so, calling :c:func:`mps_message_get` to retrieve
diff --git a/mps/manual/source/topic/telemetry.rst b/mps/manual/source/topic/telemetry.rst
index 551e6f78629..bd6f41033a0 100644
--- a/mps/manual/source/topic/telemetry.rst
+++ b/mps/manual/source/topic/telemetry.rst
@@ -78,8 +78,7 @@ now we can just call it directly from the debugger::
     $1 = void
 
 The MPS writes the telemetry to the log in an encoded form for speed.
-It can be decoded using the :ref:`eventcnv <telemetry-eventcnv>`
-program::
+It can be decoded using the :program:`eventcnv` program::
 
     (gdb) shell eventcnv | sort > mpsio.txt