Sets

Set theory - Axioms, Logic, Mathematics

Set theory - Wikipedia

Set Operations (Union, Intersection and Difference)

Python Set difference() - GeeksforGeeks

Python: Create a new empty set - w3resource

Set theory - Neumann-Bernays-Godel Axioms

Set Definition (Illustrated Mathematics Dictionary)

What are Drop Sets? Benefits and How to Use Them – Born Tough

Transfinite Numbers and Set Theory

New LEGO® Sets and Toys