diff --git a/r-in-latex.tex b/r-in-latex.tex
index 171d023..d53df5f 100644
--- a/r-in-latex.tex
+++ b/r-in-latex.tex
@@ -23,6 +23,7 @@ showstringspaces=false}
 
 \maketitle
 
+Source: http://www.damtp.cam.ac.uk/user/sje30/teaching/r/rlistings/rlistings.tex
 This short document shows you how you can include R code in your latex
 reports.  There are (probably) better ways, but this is certainly one
 good approach.  (If you come up with a nicer method, share it with the