Linked from
The 18 pages that link to Hidden-variable theory, each with the reason it gives.
Bell's theoremNarrower topic: Bell's result addresses whether such supplements can remain local.
Bell testRelated: Bell's inequality tests constrain the local versions of these theories.
Quantum nonlocalityNarrower topic: Bell's result tests whether such variables can preserve locality.
CHSH inequalityNarrower topic: The inequality tests a local subset of hidden-variable explanations.