Use \emph{} for all references to the other documents, not just some of them.

Doc/lib.tex

@@ -49,10 +49,10 @@ documented in the Reference Manual.
 
 This manual assumes basic knowledge about the Python language.  For an
 informal introduction to Python, see the \emph{Python Tutorial}; the
-Python Reference Manual remains the highest authority on syntactic and
-semantic questions.  Finally, the manual entitled \emph{Extending and
-Embedding the Python Interpreter} describes how to add new extensions
-to Python and how to embed it in other applications.
+\emph{Python Reference Manual} remains the highest authority on
+syntactic and semantic questions.  Finally, the manual entitled
+\emph{Extending and Embedding the Python Interpreter} describes how to
+add new extensions to Python and how to embed it in other applications.
 
 \end{abstract}
 

Doc/lib/lib.tex

@@ -49,10 +49,10 @@ documented in the Reference Manual.
 
 This manual assumes basic knowledge about the Python language.  For an
 informal introduction to Python, see the \emph{Python Tutorial}; the
-Python Reference Manual remains the highest authority on syntactic and
-semantic questions.  Finally, the manual entitled \emph{Extending and
-Embedding the Python Interpreter} describes how to add new extensions
-to Python and how to embed it in other applications.
+\emph{Python Reference Manual} remains the highest authority on
+syntactic and semantic questions.  Finally, the manual entitled
+\emph{Extending and Embedding the Python Interpreter} describes how to
+add new extensions to Python and how to embed it in other applications.
 
 \end{abstract}