[2] In 1976–1978 Januškevičius trained in Steklov Institute of Mathematics in Moscow, where under the guidance of Professor Vladimir Zolotarev wrote and in 1978 defended his thesis "Investigation of stability in some problems of characterization of distributions" and received the Candidate of Sciences degree.

[3] The main result of this thesis was the work of the author,[4] which considered the stability for decompositions of probability distributions into components.

For example, the assumption that two linear (or non-linear) statistics are identically distributed (or independent, or have a constancy regression and so on) can be used to characterize various populations.

Questions of this kind give rise to a following problem: determine the degree of realizability of the conclusions of mathematical statements in the case of approximate validity of conditions.

Decisions of non-homogeneous convolution equations on the half and applications for building stability estimations in characterizations of probability distributions devoted one of the major works of the author.

[10] Patriarch Alexy II during his visit to Vilnius on 25–27 July 1997 personally awarded Januškevičius with the Order of Holy Prince Daniel of Moscow of III degree[11] for the diligent work for the blessing of Orthodoxy in Lithuania in the affair of revival of spirituality.