Proof

прочный

-pročnyj

(firm or successful in resisting)

стойкий

-stojkij

(firm or successful in resisting)

упорный

-upornyj

(firm or successful in resisting)

доказа́тельство

dokazátelʹstvo

(any effort, process, or operation designed to establish or discover a fact or truth)

корректу́ра

korrektúra

(a proof sheet)

пруф

pruf

(any effort, process, or operation designed to establish or discover a fact or truth)