@article{GDZPPN001259954,
title = {On spectra of solvability and attainability for varieties of semigroups.},
journal = {Semigroup forum},
volume = {38},
year = {1989},
pages = {129-156},
zbl = {0679.20053},
url = {http://dml.mathdoc.fr/item/GDZPPN001259954}
}
Martynov, L.M. On spectra of solvability and attainability for varieties of semigroups.. Semigroup forum, Tome 38 (1989) pp. 129-156. http://gdmltest.u-ga.fr/item/GDZPPN001259954/