PSP: Custom Firmwares for Firmware 6.61 possible - Currently being updated! - Wololo.net
PSP update: 6.61, firmware, PlayStation
Infinity 2.0 released for the PSP, allows for persistent CFW on all models of PSPs on 6.60 and 6.61 | GBAtemp.net - The Independent Video Game Community
PSP CFW – ALLE MODELLE! – Yapedo MediaServices
Psp Filer 6.61 Free Download
Updating The PSP System Software to 6.60 / 6.61 - pspunk
Sony PSP receives random firmware update - SlashGear