Add links to helpful external resources.

Doc/library/functions.rst

@@ -973,6 +973,9 @@ are always available.  They are listed here in alphabetical order.
    *reverse* is a boolean value.  If set to ``True``, then the list elements are
    sorted as if each comparison were reversed.
 
+   To convert an old-style *cmp* function to a *key* function, see the
+   `CmpToKey recipe in the ASPN cookbook
+   <http://code.activestate.com/recipes/576653/>`_\.
 
 .. function:: staticmethod(function)
 

Doc/library/math.rst

@@ -93,6 +93,10 @@ Number-theoretic and representation functions
    occasionally double-round an intermediate sum causing it to be off in its
    least significant bit.
 
+   For further discussion and two alternative approaches, see the `ASPN cookbook
+   recipes for accurate floating point summation
+   <http://code.activestate.com/recipes/393090/>`_\.
+
 
 .. function:: isinf(x)