@article{Sanz-Cillero:2009zk, author = "Sanz-Cillero, Juan Jose and Guo, Zhi-Hui", title = "{Pi-pi scattering lengths at O(p^6) revisited}", doi = "10.22323/1.069.0042", journal = "PoS", year = 2009, volume = "EFT09", pages = "042" }