D. Carral, M. Krötzsch, M. Marx, A. Ozaki, and S. Rudolph. 21st International Conference on Database Theory (ICDT 2018), volume 98 of Leibniz International Proceedings in Informatics (LIPIcs), page 12:1--12:19. Dagstuhl, Germany, Schloss Dagstuhl--Leibniz-Zentrum fuer Informatik, (2018)
J. Dorn, S. Apel, and N. Siegmund. Proceedings of the 14th International Working Conference on Variability Modelling of Software-Intensive Systems, New York, NY, USA, ACM, (February 2020)