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Schmid, Hans (March 1977). "Audio Program Level, The VU Meter, and The Peak Program Meter". IEEE Transactions on Broadcasting. BC-23 (1): 22–26. doi:10.1109/TBC.1977.266233. S2CID40700960.
Schmid, Hans (March 1977). "Audio Program Level, The VU Meter, and The Peak Program Meter". IEEE Transactions on Broadcasting. BC-23 (1): 22–26. doi:10.1109/TBC.1977.266233. S2CID40700960.