ENThe article deals with relations between two trilingual dictionaries. It is based on previous researches by D. Zemzare (1961), V. Urbutis (1963/2010) and M. Beitiņa (2013a). The main aim of this article is to reveal connections between K. Sirvydas’ "Dictionarum trium linguarum" (1642) and G. Elger’s "Dictionarum polono-latino-lottauicum" (1683), as well as similarities and differences between two lexicographical methods. In order to achieve the objective, general connections between these two vocabularies are discussed first. Then relations between G. Elger’s vocabulary and G. Knapijus’ "Thesaurus" are briefly presented, i.e. additions of register and other changes to articles in vocabulary are described. The article then deals with the influence of the Polish and Latin sections on G. Elger’s and K. Sirvydas’ dictionaries. Finally, the originality of G. Elger’s vocabulary is discussed. Taking account of all the circumstances and facts of structured study, the connections between the Lithuanian and Latvian sections are evaluated. The main conclusions of this article are: 1. The fundamental source of the final G. Elger’s "Dictionarum Polono-latino-lottauicum" is K. Sirvyda’s "Dictionarum trium linguarum" 1677 edition. 2. The additional source of G. Elger’s register, Polish and Latin sections is connected with the second edition of G. Knapijus’ "Thesaurus" (1643). 3. It is quite clear that G. Knapijus’ vocabulary and related sources ("Synonym seu Dictionarum") has been used periodically. Increased influence is seen in the first part of the dictionary (especially letters B and C). Later this influence is greatly reduced – approximately from letter L, the register is almost consistent with K. Sirvydas’ register. 4. Both authors were affected by Polish lemmas and their Latin equivalents. In some places the influence ir more noticeable, elsewhere – less.5. There are only a few lexicographical innovations in G. Elger’ dictionary: basic forms of Latin words are much more distinguishable, sometimes differentiation among the meanings of Latvian words is found, and usage examples are given sporadically. 6. The research shows that G. Elger had not learned Lithuanian: he hasn’t taken up K. Sirvydas’ inventions, and descriptive compounds, which can’t show an influence from the Latin or Polish sections, are not identical. [From the publication]