Kull, K. and Salupere, S. 2026. Ivar Kull, a logician in Tartu semiotics (and on the mathematical side in Tartu semiotics of the 1960s). Sign Systems Studies. 54, 1-2 (Aug. 2026), 147–154. DOI:https://doi.org/10.12697/SSS.2026.54.1-2.08.