Hack PSP 6.20/6.35/6.39 (Permanently) with PRO-B9 [Tutorial] - YouTube
PSP Custom Firmwares 6.20 ME-1.9 and 6.20 LME-1.9 (with perma patch) are now available! - Wololo.net
4 Ways to Upgrade Your PSP Firmware - wikiHow
PSP Firmware Update Cannot be Started - Techyv.com
How to downgrade your PSP Firmware with Chronoswitch - Darthsternie's Firmware Archive
PSP Firmware 6.20 Now Live
Why do so many people prefer 6.60>6.61? : r/PSP
I was trying to downgrade my PSP go to 6.20, but it warned me that the [Resume game] feature would be deleted. Does that mean I won't be able to use the