doc-src/manual.bib

--- a/doc-src/manual.bib	Sat Feb 04 14:20:39 2012 +0100
+++ b/doc-src/manual.bib	Sat Feb 04 14:25:14 2012 +0100
@@ -1135,6 +1135,14 @@
   number =       {IC/2004/64}
 }
 
+@Article{Oppen:1980,
+  author =       {D. C. Oppen},
+  title =        {Pretty Printing},
+  journal =      {ACM Transactions on Programming Languages and Systems},
+  year =         1980,
+  volume =    2,
+  number =    4}
+
 @Manual{pvs-language,
   title		= {The {PVS} specification language},
   author	= {S. Owre and N. Shankar and J. M. Rushby},