@article{AIHPA_1999__70_1_23_0,
     author = {Borchers, H. J. and Buchholz, D.},
     title = {Global properties of vacuum states in de {Sitter} space},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {23--40},
     publisher = {Gauthier-Villars},
     volume = {70},
     number = {1},
     year = {1999},
     mrnumber = {1671209},
     zbl = {0916.53045},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPA_1999__70_1_23_0/}
}