Speicher, P., M. Steinmetz, D. Gnad, J. Hoffmann, and A. Gerevini. “Beyond Red-Black Planning: Limited-Memory State Variables”. Proceedings of the International Conference on Automated Planning and Scheduling, vol. 27, no. 1, June 2017, pp. 269-73, doi:10.1609/icaps.v27i1.13805.