References in classic literature ?
Bosquet, sent me a drawing of a perfect specimen of an unmistakeable sessile cirripede, which he had himself extracted from the chalk of Belgium.
Without interrupting his singing, or altering his devout expression, he put his hand slowly down and gave me a hard pinch--not a playful pinch, but a good hard unmistakeable pinch, such as I had never imagined possible, and then went on serenely to the next hallelujah.
His speech had been whispered, broken, and indistinct; but by a great effort he had made it plain enough to be unmistakeable.