Contractual formalities in modern contracting. No oral modification clauses and the doctrine of venire contra factum proprium as a limit to its enforceability. IUSETVERITAS [Internet]. 2023 Dec. 29 [cited 2026 Sep. 17];(67):61-75. Available from: https://revistas.pucp.edu.pe/index.php/iusetveritas/article/view/28135