1. Thomas WI, Znaniecki F (1976) Chlop polski w Europie I Ameryce. wyd. Polskie Warszawa.
2. Glorius B (2021) Social innovation within transnational flows of knowledge: The example of student mobility from Bulgaria. Popul Space Place 27: e2452. https://doi.org/10.1002/psp.2452
3. Bakalova M (2021) Education and Migration: The (Non)Return of Better Educated Migrants to Bulgaria. Economic Studies 2021: 166–186.
4. Black R, Koser K, Munk K, et al. (2004) Understanding Volun tary Return. Sussex Centre for Migration Research: Home Office, Online Report 50/04. Available from: https://webarchive.nationalarchives.gov.uk/ukgwa/20110220105210/rds.homeoffice.gov.uk/rds/pdfs04/rdsolr5004.pdf.
5. Nonchev A, Minchev V, Boshnakov V, et al., (2020) Returning migrants, UNWE Publishing complex.