A. van der Grinten, E. Angriman, M. Predari, and H. Meyerhenke. New Approximation Algorithms for Forest Closeness Centrality - for Individual Vertices and Vertex Groups. Proceedings of the 2021 {SIAM} International Conference on Data Mining, {SDM} 2021, Virtual Event, April 29 - May 1, 2021, SIAM, 2021.