Try this.
http://tech.ebu.ch/docs/r/r128.pdf
Some useful and enjoyable reading regarding "Loudness normalisation and permitted maximum level of audio signals"
At the bottom of the document there are a list of references for further reading.
[1] EBU Tech Doc 3205-E ‘The EBU standard peak-programme meter for the control of
international transmissions’
[2] ITU-R BS.645 ‘Test signals and metering to be used on international sound programme
connections’
[3] ITU-R BS.1770 ‘Algorithms to measure audio programme loudness and true-peak audio
level’
[4] EBU Tech Doc 3341 ‘Loudness Metering: ‘EBU Mode’ metering to supplement loudness
normalisation in accordance with EBU R 128’
[5] EBU Tech Doc 3342 ‘Loudness Range: A measure to supplement loudness normalisation in
accordance with EBU R 128’
[6] EBU Tech Doc 3343 ‘Practical Guidelines for Production and Implementation in accordance
with EBU R 128’
[7] EBU Tech Doc 3344 ‘Practical Guidelines for Distribution of Programmes in accordance
with EBU R 128’