How do I start studying Zero-Knowledge proofs? What are some good books and entry-level research papers on that topic? What are some prerequisites of the same?
This depends a bit on your background and what you are interested in. Philosophically speaking, zero-knowledge proofs are easy to understand (correctness, soundness and zero-knowledge), while the technical details often can be very complex. See https://en.wikipedia.org/wiki/Zero-knowledge_proof for a nice intro and non-cryptographic examples.
I think the ZKProof Community Reference (https://docs.zkproof.org/reference.pdf) gives a good intro to zero-knowledge proofs, but maybe the best (cryptographic) example is Schnorr signatures, which you can think of as a zero-knowledge proof of knowledge of the secret key corresponding to the public signing key (see e.g. https://datatracker.ietf.org/doc/html/rfc8235 or https://web.stanford.edu/class/cs259c/lectures/schnorr.pdf). This is a fundamental protocol, and many other zero-knowledge protocols (often called Sigma-protocols, see https://docs.zkproof.org/pages/standards/accepted-workshop4/proposal-sigma.pdf or https://www.cs.au.dk/~ivan/Sigma.pdf) builds upon the same structure. Finally, I can recommend this talk by Dan Boneh: https://www.youtube.com/watch?v=wB3DlND7KEw.