@article{SM_1977_33_3_a1,
     author = {V. S. Vladimirov},
     title = {Holomorphic functions with positive imaginary part in the future {tube.~IV}},
     journal = {Sbornik. Mathematics},
     pages = {301--325},
     publisher = {mathdoc},
     volume = {33},
     number = {3},
     year = {1977},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1977_33_3_a1/}
}