<ul><li><a href=https://lovdata.no/dokument/INSO/forskrift/1999-12-10-1267 target=_blank>Regulations on Civil Aviation Authority Norway(Instruks for Luftfartstilsynet, FOR-1999-12-10-1267, §3)</a></li><li><a href=https://lovdata.no/dokument/NL/lov/1993-06-11-101 target=_blank>Law on air transport(Luftfartsloven LOV-1993-06-11-101, last changed by LOV-2018-06-15-38 from 20.07.2018, §3-21  )</a></li></ul>