Release: Infinity 2.0 – Enables Permanent 6.6x Custom Firmware for all PSPs! - Wololo.net
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
How to downgrade your PSP Firmware with Chronoswitch - Darthsternie's Firmware Archive
How to Download PSP Games: 14 Steps (with Pictures) - wikiHow
How To Update Psp System Software 6.60?
Brightness control v1.6 plugin for PSP ( works on 6.20 , 6.35 , 6.39 , 6.60 and 6.61 ) : r/PSP