deletions | additions       diff --git a/Lecture_7_Externalities_this_is__.md b/Lecture_7_Externalities_this_is__.md  index 2212f05..ff24949 100644  --- a/Lecture_7_Externalities_this_is__.md  +++ b/Lecture_7_Externalities_this_is__.md 
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Here is another iteration  http://www.economistsdoitwithmodels.com/wp-content/uploads/2009/07/min-wage.jpg  One for coders  http://welkerswikinomics.com/blog/category/competition/feed/ 
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