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 * Week 5: [Crystal structure and diffraction](lecture_5.md)  
   (based on chapters 12–14, up to and including 14.2)  
   Exercises 12.3, 12.4, 13.3, 13.4 & 14.2
-* Week 6: Tight binding and nearly free electrons  
-  (based on chapters 15–16)
-* Week 7: Semiconductors  
-  (based on chapters 17–18)
-* Week 8: Magnetism  
-  (based on chapters 19-20)
+<!-- * Week 6: Tight binding and nearly free electrons   -->
+<!--   (based on chapters 15–16) -->
+<!-- * Week 7: Semiconductors   -->
+<!--   (based on chapters 17–18) -->
+<!-- * Week 8: Magnetism   -->
+<!--   (based on chapters 19-20) -->