external validity -- the resurrection as the basis of faith -- and
internal validity -- the New Testament's reliance on the Old Testament.
Both are important and interesting studies.
Here's something to think about. Do the references by Jesus, Paul, etc. to the OT indicate reliance and authenticity? Or, were they just referring to something that their hearers could relate to, much as we might refer to the 'Lord of the Rings' trilogy or Narnia Tales to illustrate a concept?
Note that there are quotations in the New Testament from the heathen poets, such as Aratus in Acts 17:28, Menander in I Corinthians 15:33, and Epimenides in Titus 1:12. Also, there are eleven margin references in the original King James Bible to Apocryphal books.
So, as we read through NT references to the OT, lets consider whether they are intended to establish and strengthen our reliance on the scriptures, or whether they are nothing more than, say, Paul's reference to the poet Menander.