Fernández-Costales Muñiz, J. 2026. Substantial Modifications of Working Conditions and Transfer of Undertakings: On the Choice of the Appropriate Procedural Route for Bringing a Claim: Commentary on Supreme Court Ruling 681/2026 of 21 July. Revista de Trabajo y Seguridad Social. CEF. 495 (Nov. 2026). DOI:https://doi.org/10.51302/rtss.2026.25596.