Objectives of firms - http://www.bing.com/videos/search?q=lorenz+curve+and+gini&mid=FE24CBF12368FBB4F940FE24CBF12368FBB4F940&FORM=LKVR6#
Cost curves for firms - http://www.youtube.com/watch?v=jNL9PNfrKZI&feature=related
Revenue curves - http://www.youtube.com/watch?v=kSoSqiqc_p8&feature=related
Monopolistic competition - http://www.youtube.com/watch?v=WRQsug1e4V4&feature=related
as above (Bryn Jones) - http://www.youtube.com/watch?v=OZhykVidmB4&feature=related
