Update README.md

README.md

@@ -131,7 +131,7 @@ for **Black-Box Optimization** (though proper benchmarking is crucial for BBO).
   [[Hansen et al., 2015]](https://link.springer.com/chapter/10.1007/978-3-662-43505-2_44),
   [[Bäck et al., 2013]](https://link.springer.com/book/10.1007/978-3-642-40137-4),
   [[Rudolph, 2012]](https://link.springer.com/referenceworkentry/10.1007/978-3-540-92910-9_22),
-  [Beyer&Schwefel, 2002](https://link.springer.com/article/10.1023/A:1015059928466),
+  [[Beyer&Schwefel, 2002]](https://link.springer.com/article/10.1023/A:1015059928466),
   [Rechenberg, 1989](https://link.springer.com/chapter/10.1007/978-3-642-83814-9_6),
   [Schwefel, 1984](https://link.springer.com/article/10.1007/BF01876146), etc.]
   * ![lso](https://img.shields.io/badge/***-lso-orange.svg) Limited-Memory Matrix Adaptation ES