Lista Real de Abidos
The Royal kinglist of Saqqara from the tomb of Tjuneroy (19th dynasty) lists nine kings for the 4th dynasty, whilst the Abydos King List gives only six names. Curiously the Saqqara-Table has after Shepseskaf two cartouches before Userkaf, but both are heavily damaged, so the original names are no longer legible. Whilst one of these two cartouches once may have held Thamphthis' name, the other cartouche remains a mystery.