What is the historical basis for the claim that there were hundreds of eyewitnesses to the resurrection of Jesus?

I've heard, in several informal situations, claims to the effect that there were hundreds of eyewitness to the resurrection of Jesus. That many saw him and even interacted with him over the span of many days after his crucifixion. However, I'm not aware of the historical basis for such claims -- if there is, I have not yet had the opportunity to have the evidence presented to me when the claim was made and I asked for the basis. Obviously, I'm fully aware of the writing of the New Testament in which Jesus is claimed to have been seen in resurrected form. For example, we have the eyewitness accounts of the authors of the gospels. We also have the book of Acts, which mentions Jesus' ascension to Heaven in chapter 1. And we also have the testimony of the apostle Paul, who had an extraordinary conversion experience in which he encountered the living Christ on his way to Damascus. So people who claimed to be eyewitnesses definitely existed, but the aforementioned cases only amount to six, not hundreds. **Question**: What is the historical basis for the claim that there were hundreds of eyewitness to the resurrection of Jesus? Are there independent eyewitness accounts, other than the six that I already mentioned, that have been preserved to this day, in which Jesus is claimed to have been seen alive, in resurrected form, after his crucifixion? Alternatively, have any writings been preserved containing **second hand** accounts? One example is [1 Cor. 15:3-8](https://www.biblegateway.com/passage/?search=1+Corinthians+15%3A3-8&version=NLT) which claims that there were over 500 witnesses to Jesus' resurrection. Are there other examples, e.g., the writings of an early church father providing a similar second hand testimony?