{"id":"S85067835","label":"Ionospheric critical frequencies","description":"","source_url":"https://id.loc.gov/authorities/subjects/sh85067835","normalized_label":"ionospheric critical frequencies","broader":["http://id.loc.gov/authorities/subjects/sh85046730","http://id.loc.gov/authorities/subjects/sh85067840","http://id.loc.gov/authorities/subjects/sh85110472"],"aliases":["Critical frequencies, Ionospheric","Penetration frequencies, Ionospheric"],"source_identifier":"http://id.loc.gov/authorities/subjects/sh85067835","provider":"lcsh","revision":"bc6b781e2695ac3b","taxonomy_revision":"f050b5d4780b1289","title":"Ionospheric critical frequencies","url":"/topics/S85067835","kind":"topic-directory","aeo_cohort":"topic-directory","catalogue_revision":"f050b5d4780b1289","numeric_address":"10124311864658756096","address_version":"morton4x16-v1","coordinates":[0,20,18464,60416],"answer_status":"Directory metadata; local answer requires separate source review","truth_status":"Subject descriptor, not a factual answer or a demonstrated knowledge gap","reviewed_answer":null}