Metamathematical discussion of some affine geometries L. Szczerba, Alfred Tarski (1979) Fundamenta Mathematicae
Model-interpretability into trees and applications. I. Korec, W. Rautenberg (1975) Archiv für mathematische Logik und Grundlagenforschung
Model-theoretic properties of cause-and-effect structures Kurt Hauschild (1982) Commentationes Mathematicae Universitatis Carolinae