1. AES. (2007). Adult Education Survey 2007: Survey data. Eurostat.
2. AES. (2011). Adult Education Survey 2011: Survey data. Eurostat.
3. AES. (2016). Adult Education Survey 2016: Survey data. Eurostat.
4. Edition ZfE;H-P Blossfeld,2020
5. Boeren, E. (2009). Adult education participation: The Matthew principle. Filosofija—Sociologija, 20(2), 154–161.