Oops forgot a bit of code for adding support for 'Letter' pubs

tripal_pub/api/tripal_pub.api.inc

@@ -1178,6 +1178,10 @@ function tripal_pub_create_citation($pub) {
         $pub_type = $ptype;
         break;
       } 
+      else if ($ptype == 'Letter') {
+        $pub_type = $ptype;
+        break;
+      } 
       else if ($ptype == 'Book Chapter') {
         $pub_type = $ptype;
         break;
@@ -1326,4 +1330,4 @@ function tripal_pub_create_citation($pub) {
   }
 
   return $citation;
-}
+}