Case C-866/19: Judgment of the Court (Third Chamber) of 21 October 2021 (request for a preliminary ruling from the Sąd Najwyższy — Poland) — SC v Zakład Ubezpieczeń Społecznych I Oddział w Warszawie (Reference for a preliminary ruling — Social security for migrant workers — Regulation (EC) No 883/2004 — Article 52(1)(b) — Worker who has been employed in two Member States — Minimum period required by national law for acquisition of entitlement to a retirement pension — Account taken of the contribution period completed under the legislation of another Member State — Aggregation — Calculation of the amount of the retirement benefit to be paid)