DIN 45635-40:1987 Measurement of airborne noise emitted by machines; enveloping surface method; machine sets in hydroelectric power stations and water pumping plants
1987DIN 45635-40:1987-03 Measurement of airborne noise emitted by machines; enveloping surface method; machine sets in hydroelectric power stations and water pumping plants
1987DIN 45635-40:1987 Measurement of airborne noise emitted by machines; enveloping surface method; machine sets in hydroelectric power stations and water pumping plants