@article{MZM_1998_63_4_a17,
     author = {V. G. Kanovei and J. Zapletal},
     title = {Pyramidal structure of constructibility degrees},
     journal = {Matemati\v{c}eskie zametki},
     pages = {632--635},
     publisher = {mathdoc},
     volume = {63},
     number = {4},
     year = {1998},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1998_63_4_a17/}
}