@article{AL_2020_59_4_a4,
     author = {A. S. Morozov and D. A. Tussupov},
     title = {Minimal predicates for $\Delta$-definability},
     journal = {Algebra i logika},
     pages = {480--499},
     publisher = {mathdoc},
     volume = {59},
     number = {4},
     year = {2020},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_2020_59_4_a4/}
}