Church's Theorem, showing the undecidability of first order logic, appeared in A note on the Entscheidungsproblem published in the first issue of the Journal of Symbolic Logic.
Simbahan ng teorama, na nagpapakita ng undecidability ng unang order na lohika, lumabas sa isang tanda sa Entscheidungsproblem-publish sa unang isyu ng Journal ng sinasagisag Logic.