Terms for subject General containing неизвестно откуда

Russian	English
неизвестно откуда	from where no one knows (While the members stood about in the yard in open-mouthed wonder, other stones pelted the house, coming from where no one knows. (Janet & Colin Bord, "Unexplained Mysteries of The 20th Century") ART Vancouver)
неизвестно откуда взявшийся	undreamt-of
Неизвестно откуда вынырнул человек в форме	a man in uniform came out of nowhere