Yeshkeyev, A. R., M. T. Kassymetova, and O. I. Ulbrikht. “On the Jonsson Pairs of Abelian Groups in the Enriched Language”. Journal of Mathematics, Mechanics and Computer Science, vol. 95, no. 3, Aug. 2018, pp. 32-49, doi:10.26577/jmmcs-2017-3-466.