Daniel Packer, Sophia White, Aaron Williams. A Paper on Pencils: A Pencil and Paper Puzzle - Pencils is NP-Complete. In Stephane Durocher, Shahin Kamali, editors, Proceedings of the 30th Canadian Conference on Computational Geometry, CCCG 2018, August 8-10, 2018, University of Manitoba, Winnipeg, Manitoba, Canada. pages 35-41, 2018. [doi]
Abstract is missing.