@article{10_4171_ggd_618,
     author = {James Dibble},
     title = {Abelian subgroups of the fundamental group of a space with no conjugate points},
     journal = {Groups, geometry, and dynamics},
     pages = {683--690},
     year = {2021},
     volume = {15},
     number = {2},
     doi = {10.4171/ggd/618},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/ggd/618/}
}