Update publications.md

docs/examples/publications.md

@@ -12,4 +12,5 @@ MO-Gymnasium (formerly MO-Gym) was first published in:
 List of publications & submissions using MO-Gymnasium (please open a pull request to add missing entries):
 - [Sample-Efficient Multi-Objective Learning via Generalized Policy Improvement Prioritization](https://arxiv.org/abs/2301.07784) (Alegre et al., AAMAS 2023)
 - [Hyperparameter Optimization for Multi-Objective Reinforcement Learning](https://arxiv.org/abs/2310.16487v1) (Felten et al., MODeM Workshop 2023)
+- [Multi-Step Generalized Policy Improvement by Leveraging Approximate Models](https://openreview.net/forum?id=KFj0Q1EXvU) (Alegre et al., NeurIPS 2023)
 - [A Toolkit for Reliable Benchmarking and Research in Multi-Objective Reinforcement Learning](https://openreview.net/forum?id=jfwRLudQyj) (Felten et al., NeurIPS 2023)