As requested by Bruce [here](https://forum.keka.io/viewtopic.php?f=6&p=2984#p2984). - https://en.wikipedia.org/wiki/Blu-ray - http://www.hughsnews.ca/faqs/authoritative-blu-ray-disc-bd-faq/9-disc-capacity
As requested by Bruce here.