Sony Updates Its PSP Console with Firmware 6.61 – Download Links Available
Install or use custom firmware on any 6.39 PSP [PSP, PSP Slim, PSP 3000, PSP Go] | Digiex
How to downgrade your PSP Firmware with Chronoswitch - Darthsternie's Firmware Archive
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: Infinity 2.0 – Permanent 6.61 Custom Firmware for every PSP! - YouTube
POC: PSP 3000 CFW 6.61 Infinity
How To Easy Jailbreak Any PSP 6.61 CFW Permanent - Consoleinfo