00504nam a22001577a 4500008004500000020001800045082001600063100002900079245007100108250001200179260003900191300001400230650003900244650003300283650003000316230615b    2022       ||||| |||| 00| 0 eng d  a9780707747347  a 623.8bUKH  a UK Hydrographic Office.  aAdmiralty List of Radio Signals : Maritime Radio Stations Volume 1  a3rd ed.  aUKb UK Hydrographic Office.c2022  axx, 464p.  aPurpose of Admiralty Radio Signals  aGlobal Communication Network  aMaritime Security Threats