Lai, Katherine, Carla Gomes, Michael Schwartz, Kevin McKelvey, David Calkin, and Claire Montgomery. 2011. “The Steiner Multigraph Problem: Wildlife Corridor Design for Multiple Species”. Proceedings of the AAAI Conference on Artificial Intelligence 25 (1):1357-64. https://doi.org/10.1609/aaai.v25i1.7809.