In the period between 1935 and 1950, most papers were written along the lines suggested by Birkhoff's papers, dealing with free algebras, congruence and subalgebra lattices, and homomorphism theorems. Although the development of mathematical logic had made applications to algebra possible, they came about slowly; results published by Anatoly Maltsev in the 1940s went unnoticed because of the war. Tarski's lecture at the 1950 International Congress of Mathematicians in Cambridge ushered in a new period in which model-theoretic aspects were developed, mainly by Tarski himself, as well as C.C. Chang, Leon Henkin, Bjarni Jónsson, Roger Lyndon, and others.
iN tHE period betwEEn 1935 aNd 1950, moSt Papers were WriTtEN aLOng the liNes sugGESteD BY birkhOfF's paPers, deaLiNg with FrEe ALGebRas, conGruence AnD subAlGebRa Lattices, and HomOMorphism theorems. althOUgh tHe DeVeLopment Of maTHemAticAl loGIC had Made apPlicatiONs To algebrA pOSsible, they camE AbOut slowLY; ResUltS pUblIshed by aNatOlY maltSeV in the 1940s weNt UnNoTiced BecaUsE of The War. TArski's lEcture at The 1950 InteRnAtional COngREss of maThemAticIANs In cambridge uSheRed in a neW peRiod in WhiCH model-TheoreTiC Aspects WeRe devEloped, mainlY by tArski HimsElf, as WelL aS c.c. chaNG, Leon heNkiN, bjARNI jóNsson, rogER lyndoN, anD oTHeRs.