1. General Data Protection Regulation (EU) 2016/679, Article 2(1): "This Regulation applies to the processing of personal data wholly or partly by automated means and to the processing other than by automated means of personal data which form part of a filing system or are intended to form part of a filing system."
2. General Data Protection Regulation (EU) 2016/679, Article 4(6): "'filing system' means any structured set of personal data which are accessible according to specific criteria, whether centralised, decentralised or dispersed on a functional or geographical basis."
3. General Data Protection Regulation (EU) 2016/679, Recital 15: "The protection of natural persons should apply to the processing of personal data by automated means, as well as to manual processing, if the personal data are contained or are intended to be contained in a filing system."
4. Voigt, P., & von dem Bussche, A. (2017). The EU General Data Protection Regulation (GDPR): A Practical Guide. Springer. In Chapter 3, Section 3.2.1 on Material Scope, the authors explain that "the GDPR also applies to non-automated processing of personal data, if they are stored in a filing system or are intended to be stored in a filing system... A filing system requires a structured set of personal data which are accessible according to specific criteria." (p. 21). DOI: https://doi.org/10.1007/978-3-319-57959-7