The "24th problem" (in proof theory, on a criterion for simplicity and general methods) was rediscovered in Hilbert's original manuscript notes by German historian Rüdiger Thiele  in 2000.
"Det 24. problem", der omhandlede et kritierie for simplicitet og generelle metoder i bevisteori, blev genopdaget i Hilberts originale manuskriptnoter af den tyske historiker Rüdiger Thiele i 2000.