- A few pages from "Intro to Commutative ..." by
Kunz

- "Initial Results in the
theory of linear algebraic groups" by Rosenlicht

- "Notes on difference
equations" by Singer (the prequil to "Galois Theory of
Difference Equations")

- "Solving difference equations in finite terms" by Hendriks and Singer
- "An Algorithm for determining the difference Galois group of second order difference equations""by Hendriks
- "Quantum Automata and Algebraic Groups" by Derksen et al
- "Hypergeometric solutions
of linear recurrences with polynomial coefficients"by
Petkovsek

and here are the lecture notes for the course.