Every PSVita Firmware that has been released up until now. If you are searching for ePSP related things like VHBL, TN-V and more, it will take me some time to add all epsp files to the download list so please use the folder link Below:
PSVita ePSP Files

Normal Firmwares
Preinstalled Firmwares
Systemdata Firmwares
Complete Official Firmwares
PSVita Partition Files