https://www.reuters.com/article/us-facebook-cambridge-analytica/zuckerberg-apologizes-for-facebook-mistakes-with-user-data-vows-curbs-idUSKBN1GX0OG >Facebook Inc Chief Executive Mark Zuckerberg apologized on Wednesday for mistakes his company made in how it handled data belonging to 50 million of its users and promised tougher steps to restrict developers' access to such information.