@article{10_4007_annals_2017_185_1_7,
     author = {Ernie Croot and Vsevolod F. Lev and P\'eter P\'al Pach},
     title = {Progression-free sets in $\mathbb Z_4^n$ are exponentially small},
     journal = {Annals of mathematics},
     pages = {331--337},
     publisher = {mathdoc},
     volume = {185},
     number = {1},
     year = {2017},
     doi = {10.4007/annals.2017.185.1.7},
     mrnumber = {3583357},
     zbl = {06686589},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4007/annals.2017.185.1.7/}
}