2021DS/EN IEC 61828:2021 Ultrasonics – Transducers – Definitions and measurement methods regarding focusing for the transmitted fields
2002DS/EN 61828:2002 Ultrasonics - Focusing transducers - Definitions and measurement methods for the transmitted fields
DS/EN IEC 61828:2021 Ultrasonics – Transducers – Definitions and measurement methods regarding focusing for the transmitted fields was changed to DS/EN 61828:2002 Ultrasonics - Focusing transducers - Definitions and measurement methods for the transmitted fields.