Fix some ReST errors and missing/duplicate references in docs.

CHANGES.rst

@@ -1272,7 +1272,7 @@ Bugs fixed
 * Compile errors and warnings in integer type conversion code.  This fixes
   ticket 877.  Patches by Christian Neukirchen, Nikolaus Rath, Ian Henriksen.
 
-* Reference leak when "*args" argument was reassigned in closures.
+* Reference leak when ``*args`` argument was reassigned in closures.
 
 * Truth-testing Unicode strings could waste time and memory in Py3.3+.
 

docs/src/quickstart/build.rst

@@ -105,4 +105,5 @@ Using the Sage notebook
 
 
 .. [Jupyter] https://jupyter.org/
-.. [Sage] W. Stein et al., Sage Mathematics Software, https://www.sagemath.org/
+..
+   [Sage] W. Stein et al., Sage Mathematics Software, https://www.sagemath.org/

docs/src/tutorial/related_work.rst

@@ -41,7 +41,8 @@ Python modules.
 
 .. [ctypes] https://docs.python.org/library/ctypes.html.
 .. there's also the original ctypes home page: http://python.net/crew/theller/ctypes/
-.. [Pyrex] G. Ewing, Pyrex: C-Extensions for Python,
+..
+   [Pyrex] G. Ewing, Pyrex: C-Extensions for Python,
    https://www.cosc.canterbury.ac.nz/greg.ewing/python/Pyrex/
 .. [ShedSkin] M. Dufour, J. Coughlan, ShedSkin,
    https://github.com/shedskin/shedskin

docs/src/userguide/extension_types.rst

@@ -850,6 +850,7 @@ use the C-API equivalent of::
 
 instead of the desired C equivalent of ``return f->f0 + f->f1 + f->f2``. We can
 alias the fields by using::
+
     cdef extern from "foo_nominal.h":
 
         ctypedef class foo_extension.Foo [object FooStructNominal]:

docs/src/userguide/memoryviews.rst

@@ -20,6 +20,9 @@ A memoryview can be used in any context (function parameters, module-level, cdef
 class attribute, etc) and can be obtained from nearly any object that
 exposes writable buffer through the `PEP 3118`_ buffer interface.
 
+.. _`PEP 3118`: https://www.python.org/dev/peps/pep-3118/
+
+
 .. _view_quickstart:
 
 Quickstart
@@ -226,6 +229,8 @@ NumPy arrays support this interface, as do :ref:`view_cython_arrays`.  The
 data array to themselves be pointers; Cython memoryviews do not yet support
 this.
 
+.. _`new style buffers`: https://docs.python.org/3/c-api/buffer.html
+
 .. _view_memory_layout:
 
 Memory layout