@article{Colangelo:2023X+, author = "Colangelo, Gilberto and Hoferichter, Martin and Stoffer, Peter", title = "{Puzzles in the hadronic contributions to the muon anomalous magnetic moment}", doi = "10.22323/1.452.0019", journal = "PoS", year = 2023, volume = "Muon4Future2023", pages = "019" }