EPC, “Article 54 – Novelty”, n.d. https://www.epo.org/en/legal/epc/2020/a54.html.

Following the European Patente Convention (EPC, Article 54 – Novelty), "the state of the art shall be held to comprise everything made available to the public by means of a written or oral description, by use, or in any other way, before the date of filing of the European patent application"

https://www.epo.org/en/legal/epc/2020/a54.html.