Abeywickrama, Tenindra, Muhammad Aamir Cheema, and Sabine Storandt. 2020. “Hierarchical Graph Traversal for Aggregate K Nearest Neighbors Search in Road Networks”. Proceedings of the International Conference on Automated Planning and Scheduling 30 (1):2-10. https://ojs.aaai.org/index.php/ICAPS/article/view/6639.