@article{SIGMA_2020_16_a90,
     author = {Felix Finster},
     title = {The {Causal} {Action} in {Minkowski} {Space} and {Surface} {Layer} {Integrals}},
     journal = {Symmetry, integrability and geometry: methods and applications},
     year = {2020},
     volume = {16},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SIGMA_2020_16_a90/}
}