HADI, SUPRIYONO and AGUS, SUBARDI and I MADE, WAHYU SANDIKA (2020) Global Maritime Distress and Safety System (GMDSS) FOR RADIO OPERATOR. POLITEKNIK ILMU PELAYARAN SEMARANG, SEMARANG. ISBN ISBN: 978-623-7445-28-9 e-ISBN: 978-623-7445-38-8