Added more cross-references.

Doc/library/collections.rst

@@ -405,10 +405,14 @@ Setting the :attr:`default_factory` to :class:`set` makes the
           print record
 
    To cast an individual record stored as :class:`list`, :class:`tuple`, or some
-   other iterable type, use the star-operator to unpack the values::
+   other iterable type, use the star-operator [#]_ to unpack the values::
 
       >>> Color = NamedTuple('Color', 'name code')
       >>> m = dict(red=1, green=2, blue=3)
       >>> print Color(*m.popitem())
       Color(name='blue', code=3)
 
+.. rubric:: Footnotes
+
+.. [#] For information on the star-operator see
+   :ref:`tut-unpacking-arguments` and :ref:`calls`.

Doc/library/fpformat.rst

@@ -12,8 +12,8 @@ numbers representations in 100% pure Python.
 
 .. note::
 
-   This module is unneeded: everything here could be done via the ``%`` string
-   interpolation operator.
+   This module is unnecessary: everything here can be done using the ``%`` string
+   interpolation operator described in the :ref:`string-formatting` section.
 
 The :mod:`fpformat` module defines the following functions and an exception:
 

Doc/library/stringio.rst

@@ -8,7 +8,8 @@
 
 This module implements a file-like class, :class:`StringIO`, that reads and
 writes a string buffer (also known as *memory files*).  See the description of
-file objects for operations (section :ref:`bltin-file-objects`).
+file objects for operations (section :ref:`bltin-file-objects`). (For
+standard strings, see :class:`str` and :class:`unicode`.)
 
 
 .. class:: StringIO([buffer])