diff --git a/KN02/challenge_a/KN02a_1.md b/KN02/challenge_a/KN02a_1.md
index 9956731..85c576b 100644
--- a/KN02/challenge_a/KN02a_1.md
+++ b/KN02/challenge_a/KN02a_1.md
@@ -402,9 +402,6 @@ Beachten Sie ausserdem die [allgemeinen Informationen zu den Abgaben](../Abgaben
 
 ### Quellen
 
-Thorntech: [Passwords vs. SSH keys - what's better for authentication?](https://thorntech.com/passwords-vs-ssh)
-
-
 <br>
 
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