@inproceedings{Nierste:2017oZ, author = "Nierste, Ulrich", title = "{Penguin pollution in $\beta$ and $\beta_s$}", doi = "10.22323/1.291.0081", booktitle = "Proceedings of 9th International Workshop on the CKM Unitarity Triangle {\textemdash} PoS(CKM2016)", year = 2017, volume = "291", pages = "081" }