Good Non-Technical Introductions to RDF?

[David Booth]

Do you know of any good non-technical introductions to RDF?  I have 
started a list (with reviews), but I feel like there must be many more 
that I have not yet found:
https://goo.gl/z7uOn5
Suggestions?   Please also feel free to make edit suggestions directly 
to that document.

Thanks,
David Booth