Big data analytics 9th International Conference, BDA 2021, virtual event, December 15-18, 2021 : proceedings - Srirama, Satish Narayana 1978-; Lin, Jerry Chun-Wei ca. 20./21. Jh; Bhatnagar, Raj; Agarwal, Sonali; Krishna Reddy, P. 1965- (Information systems and applications, incl. internet/web, and HCI, 2021)