Acknowledged Carsten Clasohm

--- a/doc-src/Ref/ref.tex	Fri Dec 03 12:47:45 1993 +0100
+++ b/doc-src/Ref/ref.tex	Fri Dec 03 17:43:49 1993 +0100
@@ -9,6 +9,7 @@
 
 \author{{\em Lawrence C. Paulson}\thanks
 {Tobias Nipkow, of T. U. Munich, wrote Chapter~8 and part of Chapter~6.
+ Carsten Clasohm also contributed to Chapter~6.
  Sara Kalvala and Markus Wenzel suggested changes and corrections.
  The research has been funded by the SERC (grants GR/G53279, GR/H40570)
   and by ESPRIT project 6453: Types).}