I have a question:
Given a field $k$, finite or infinite, and an element $p(t)$ in the polynomial ring $k[t]$.
I am searching for results of any kind about how to find quadratic residues in the quotient ring $k[t]/⟨p(t)⟩$, if they exist. Can anyone recommend a good book/paper on that topic?
(There is an answer in: Literature on Quadratic Residues in Polynomial Quotient ring for this same question with a link that does not work.)