- The Map of Mathematics
- euclideanspace - Maths - Abstract Algebra and Discrete Mathematics
- Five Stages of Constructive Mathematics - Andrej Bauer
- What Does It Mean to Be a Number? (The Peano Axioms) | Infinite Series
- Abstract Algebra on Socratica
- Algebra - Saunders Mac Lane
- Category Theory for Programmers playlist - Part 1
- Category Theory for Programmers blog - Part 1 - My Answers to Challenges
- Category theory foundations — Steve Awodey
- Cakes, Custard and Category Theory - Chapter: universal properties
- Category Theory for Programmers playlist - Part 2
- Category Theory for Programmers blog - Part 2
- Category Theory for Programmers playlist - Part 3
- Category Theory for Programmers blog - Part 3
- Conceptual Mathematics - A First Introduction to Categories
- Automata and Coinduction (an exercise in coalgebra) - J.J.M.M Rutten
- A Tutorial on Coalgebras and Coinduction
- Kleene Coalgebra: an overview - Alexandra Silva, Marcello Bonsangue and Jan Rutten
- Fundamental Study: Universal Coalgebra: A theory of systems
- The basics of coinduction - Jan Stolarek
- Propositions as Types - Computerphile - Altenkirch
- Type Theory Foundations
- Types and Programming Languages
- Practical Foundations for Programming Languages
- Oleg Kiselyov's site
- Adventures with Types
- SQL in the type system where it belongs
- Structural type system
- Polymorphism, Subtyping, and Type Inference in MLsub