Useful links for paperclip gem in rails

 Ruby on Rails 4.0, Amazon S3, Paperclip and Heroku  
 http://www.blitztheory.com/direct-upload-with-s3_direct_upload/  
 http://dev.mensfeld.pl/2013/12/rails-paperclip-open-uri-downloading-files-from-the-internet-and-saving-them-with-paperclip/  
 http://asciicasts.com/episodes/134-paperclip  
 http://patshaughnessy.net/2010/5/23/how-to-install-paperclip-in-a-rails-3-app  
 rails 4  
 http://robmclarty.com/blog/how-to-install-image-magick-and-setup-paperclip  
 rails 3  
 http://codeabout.wordpress.com/2011/03/08/gem-paperclip-uploading-files-and-pictures-into-your-rails-application/  
 https://devcenter.heroku.com/articles/paperclip-s3  
 http://railscasts.com/episodes/134-paperclip