@article{IVM_2013_11_a6,
     author = {A. N. Frolov},
     title = {A note on $\Delta_2^0$-spectra of linear orderings and degree spectra of the successor relation},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {74--78},
     publisher = {mathdoc},
     number = {11},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2013_11_a6/}
}