--- a/refs.xsl	Thu Apr 06 17:24:30 2017 +0100
+++ b/refs.xsl	Thu Apr 06 18:31:46 2017 +0100
@@ -41,13 +41,13 @@
                 else $bit
             else ()"/>
    <ref c="{@r}">
-    <xsl:for-each select="$singles">
+    <xsl:for-each select="distinct-values($singles)">
      <s><xsl:value-of select="."/></s>
     </xsl:for-each>
-    <xsl:for-each select="$ranges">
+    <xsl:for-each select="distinct-values($ranges)">
      <r><xsl:value-of select="."/></r>
     </xsl:for-each>
-    <xsl:for-each select="$externals">
+    <xsl:for-each select="distinct-values($externals)">
      <e><xsl:value-of select="."/></e>
     </xsl:for-each>
    </ref></xsl:if>