Full Idea
In propositional logic, any set containing ¬ and at least one of ∧, ∨ and → is expressively complete.
Gist of Idea
Propositional logic just needs ¬, and one of ∧, ∨ and →
Source
José L. Zalabardo (Introduction to the Theory of Logic [2000], §2.8)
Book Reference
Zalabardo,José L.: 'Introduction to the Theory of Logic' [Westview 2000], p.71