@article{AL_1973_12_2_a1,
     author = {A. N. Degtev},
     title = {$tt$- and $m$-degrees},
     journal = {Algebra i logika},
     pages = {143--161},
     publisher = {mathdoc},
     volume = {12},
     number = {2},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/AL_1973_12_2_a1/}
}