References in classic literature ?
Such unintermitted strainings upon the planted iron must sooner or later inevitably extract it.
George remained four years at a French university, and, applying himself with an unintermitted zeal, obtained a very thorough education.
In Section 37 Whitman's persona describes himself as "possess'd," embodying "all presences outlaw'd or suffering," seeing himself "in prison shaped like another man," and feeling "the dull unintermitted pain" (LGVar.