§ 4 NDSG
Notice where data are collected from other persons
(1)1Where personal data are collected not from the data subject but from another person or a body outside the public sector, the purpose of the collection shall, upon request, be communicated to that other person or body, insofar as this does not prejudice the legitimate interests of the data subject. 2Where a duty to provide information exists, the person shall be informed thereof; otherwise the person shall be informed of the voluntary nature of his or her information.