Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
공중자기의 측정은 지구의 자기장을 연구하는 데 중요하다.Gongjungjagiui cheugjeong-eun jigu-ui jagijang-eul yeonguhaneun de jungyohada.Aeromagnetic measurements are important for studying the Earth's magnetic field.