Bredereck, R., P. Faliszewski, A. Kaczmarczyk, D. Knop, and R. Niedermeier. “Parameterized Algorithms for Finding a Collective Set of Items”. Proceedings of the AAAI Conference on Artificial Intelligence, vol. 34, no. 02, Apr. 2020, pp. 1838-45, doi:10.1609/aaai.v34i02.5551.