Bibliography+10

1. http://www.youtube.com/watch?v=Jax-ZyL7DkI 2. http://johnleanomics.wordpress.com/2009/03/06/externalities/ 3. http://johnleanomics.wordpress.com/2009/03/06/externalities/ 4. http://welkerswikinomics.com/blog/wp-content/uploads/2008/01/pollution-permits_1 5. http://www.youtube.com/watch?v=7jdvnSm48nY