Update tutorials.rst

docs/sphinx/source/tutorials/tutorials.rst

@@ -789,7 +789,10 @@ on their corresponding `API <https://pypop.readthedocs.io/_/downloads/en/latest/
 documentations and two *testing* code (if possible) on their corresponding `source code
 <https://github.com/Evolutionary-Intelligence/pypop/tree/main/pypop7/optimizers>`_ folders.
 
-.. note:: "Again unfortunately, there does not exist an agreed-upon test problem catalogue to evaluate old aswell as new algorithms in a concise way. It is doubtful whether such a test bed will ever be agreed uponbut efforts in that direction would be worthwhile."---[Schwefel, 1997]
+.. note:: `"Unfortunately, there does not exist an agreed-upon test problem catalogue to evaluate
+   old as well as new algorithms in a concise way. It is doubtful whether such a test bed will
+   ever be agreed upon but efforts in that direction would be worthwhile."---[Schwefel, 1997]
+   <https://www.taylorfrancis.com/books/edit/10.1201/9780367802486/handbook-evolutionary-computation-fogel-michalewicz-thomas-baeck>`_
 
 .. image:: https://visitor-badge.laobi.icu/badge?page_id=Evolutionary-Intelligence.pypop-tutorials
    :target: https://visitor-badge.laobi.icu/badge?page_id=Evolutionary-Intelligence.pypop-tutorials