Szewczyk-Jarocka, Mariola, et al. “UNREGISTERED EMPLOYMENT IN THE LOCAL LABOUR MARKET: CASE STUDY OF PŁOCK”. Acta Scientiarum Polonorum. Oeconomia, vol. 20, no. 1, June 2021, pp. 71-79, doi:10.22630/ASPE.2021.20.1.7.