diff --git a/coope.sty b/coope.sty
index 8367db0..a312b03 100644
--- a/coope.sty
+++ b/coope.sty
@@ -24,6 +24,9 @@
 \newcommand{\jsref}{\textmd Listing~\ref}
 \newcommand{\fref}{\textmd Figure~\ref}
 
+% denotes a non-free reference (to be used in .bib file)
+\newcommand{\citenf}{\textbf[NF]}
+
 \lstdefinelanguage{JavaScript}{%
   keywords={%
     undefined,null,true,false,NaN,Infinity,return,%