@article{AIHPA_1998__69_2_189_0,
     author = {Unterberger, Andr\'e},
     title = {A calculus of observables on a {Dirac} particle},
     journal = {Annales de l'I.H.P. Physique th\'eorique},
     pages = {189--239},
     publisher = {Gauthier-Villars},
     volume = {69},
     number = {2},
     year = {1998},
     mrnumber = {1638891},
     zbl = {0914.35114},
     language = {en},
     url = {http://archive.numdam.org/item/AIHPA_1998__69_2_189_0/}
}