diff --git a/seed/challenges/advanced-bonfires.json b/seed/challenges/advanced-bonfires.json
index 58f6602791..f729bde4e2 100644
--- a/seed/challenges/advanced-bonfires.json
+++ b/seed/challenges/advanced-bonfires.json
@@ -87,7 +87,8 @@
         "assert.deepEqual(sym([1, 1]), [1], 'should return an array of unique values');"
       ],
       "MDNlinks": [
-        "Array.reduce()"
+        "Array.reduce()",
+        "Symmetric Difference"
       ],
       "challengeType": 5,
       "nameCn": "",