From what I understand the values varies a little from engine to engine. Much as Joe Wilson writes in http://www.marmoset.co/toolbag/learn/pbr-practice. "PBR is more of a concept than a strict set of rules, and as such, the exact implementations of PBR systems tend to vary. "
Don't let yourself be too bothered by exact values for one particular solution when starting out. Those values are meaningless in any other shader than the one you are using. It is better to spend that time understanding the basics physics surface and light interaction. The best points I can give you are: Understand the…