OBS_VALUE: <ul><li><a href=https://isap.sejm.gov.pl/isap.nsf/DocDetails.xsp?id=wdu20030860789 target=_blank>Act of the 28th March 2003 on railway transport(Ustawa z dnia 28 marca 2003 r. o transporcie kolejowym, Dz. U. z 2015 r., poz. 1297,Dz. U. z 2017 r. poz. 2117, 2361, z 2018 r, poz. 650., 28 March 2003, last updated on 19 April 2022, Chapter 4, Article 22)</a></li><li><a href=http://ec.europa.eu/growth/tools-databases/regprof/index.cfm?action=regprof&id_regprof=7247&id_profession=12288&tab=countries&id_country=23&quid=2&mode=asc&pagenum=1 target=_blank>Website of the European Commission, The EU Single Market, Regulated professions database, Poland</a></li></ul>