Samsung S4

http://www.trickyways.com/2014/05/downgrade-samsung-galaxy-s4-i337-att-android-4.2.2-jelly-beans-stock-firmware/

http://www.theandroidsoul.com/back-stock-get-official-android-4-3-update-att-galaxy-s4-sgh-i337-i337mumuemk6-50943/

http://galaxys4root.com/galaxy-s4-stock-firmware/