Fix a broken link.

native_client_sdk/src/doc/nacl-and-pnacl.rst

 .. _nacl-and-pnacl:
 
 ##############
 NaCl and PNaCl
 ##############
 
 This document describes the differences between **Native Client** and
 **Portable Native Client**, and provides recommendations for when to use each.
 
 .. contents::
   :local:
   :backlinks: none
   :depth: 2
 
 Native Client (NaCl)
 ====================
 
 Native Client enables the execution of native code securely inside web
 applications through the use of advanced `Software Fault Isolation (SFI)
-techniques </native-client/community/talks#research>`_.  Since its launch in
+techniques <http://research.google.com/pubs/pub35649.html>`_.  Since its launch in
 2011, Native Client has provided developers with the ability to harness a
 client machine's computational power to a much fuller extent than traditional
 web technologies, by running compiled C and C++ code at near-native speeds and
 taking advantage of multiple cores with shared memory.
 
 While Native Client provides operating system independence, it requires
 developers to generate architecture-specific executable 
 (**nexe**) modules for each hardware platform. This is not only inconvenient
 for developers, but architecture-specific machine code is not portable and thus
 not well-suited for the open web. The traditional method of application
@@ skipping 74 matching lines @@
   instructions in an application (i.e., inline assembly), but tries to
   offer high-performance portable equivalents. One such example is
   PNaCl's :ref:`Portable SIMD Vectors <portable_simd_vectors>`.
 * PNaCl only supports static linking with the ``newlib``
   C standard library (the Native Client SDK provides a PNaCl port of
   ``newlib``). Dynamic linking and ``glibc`` are not yet supported.
   Work is under way to enable dynamic linking in future versions of PNaCl.
 * PNaCl does not support some GNU extensions
   like taking the address of a label for computed ``goto``, or nested
   functions.