Focus
Bokeh depth of field – going insane! part 1 - 2014
The Skylanders SWAP Force Depth-of-Field Shader - 2013
Current-gen DOF and MB - 2012
Gpu Gems 3: Chapter 28. Practical Post-Process Depth of Field - 2006
Gpu Gems: Chapter 23. Depth of Field: A Survey of Techniques - 2004