Remarks on Zasada efektywności W Prawie międzynarodowym [Principle of Effectiveness in International Law] by Janusz Symonides: On the Anniversary of the Conclusion of the Polish-German Treaties of 1950, 1970 and 1990. PYIL 2021, 40, 23-38. https://doi.org/10.24425/pyil.2021.138427.