@article{CMH_1987__62_140095,
     author = {V. Bangert},
     title = {A uniqueness theorem for {Zn-periodic} variational problems.},
     journal = {Commentarii mathematici Helvetici},
     pages = {511--531},
     publisher = {mathdoc},
     volume = {62},
     year = {1987},
     zbl = {0634.49018},
     url = {http://geodesic.mathdoc.fr/item/CMH_1987__62_140095/}
}