@article{AIHPC_1989__S6__365_0,
     author = {Lawrence, J. and Spingarn, J. E.},
     title = {An intrinsic characterization of foldings of euclidean space},
     journal = {Annales de l'I.H.P. Analyse non lin\'eaire},
     pages = {365--383},
     publisher = {Gauthier-Villars},
     volume = {S6},
     year = {1989},
     mrnumber = {1019122},
     zbl = {0676.51005},
     language = {en},
     url = {http://www.numdam.org/item/AIHPC_1989__S6__365_0/}
}