@article{AL_1990_29_6_a2,
     author = {Yu. L. Ershov},
     title = {Forcing in admissible sets},
     journal = {Algebra i logika},
     pages = {648--658},
     publisher = {mathdoc},
     volume = {29},
     number = {6},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1990_29_6_a2/}
}