International Telecommunication Union – Radiocommunication Sector (ITU-R) – https://www.itu.int/en/ITU-R/Pages/default.aspx
Ministry of Industry and Trade (MIT) – E-Comm and Postal Services – https://mpo.gov.cz/en/e-communications-and-postal-services/
Czech Telecommuánication Office (CTO) – Amateur radiocommunication service, https://ctu.gov.cz/en/how-get-professional-competence-certificate-or-individual-authorisation-utilise-frequencies-operate
IARU – International Amateur Radio Union – https://www.iaru.org/
AMSAT – The Radio Amateur Satellite Corporation – https://www.amsat.org/
ARRL – The National Association for Amateur Radio – https://www.arrl.org/
DUBUS -Magazine for VHF and up amateur radio – http://dubus.org/