Lesson4Week6.markdown

@@ -111,4 +111,4 @@ Lastly, we will check if it Is possible to use the color sensor for both followi
 
 ### References
 1. Sourcecode for the programs in this lesson can be found in Lesson4programs.zip.
-2. [A PID Controller For Lego Mindstorms Robots.](http://www.inpharmix.com/jps/PID_Controller_For_Lego_Mindstorms_Robots.html]
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+2. [A PID Controller For Lego Mindstorms Robots.](http://www.inpharmix.com/jps/PID_Controller_For_Lego_Mindstorms_Robots.html)
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