There's always been a lot of discussion about page metadata and microdata but never any conclusion.

At some point I was tricked into believing that it.source used microdata (https://it.wikisource.org/wiki/Progetto:Qualità/Semantizzazione ?), but clearly it doesn't.
https://www.google.com/webmasters/tools/richsnippets?q=https%3A%2F%2Fit.wikisource.org%2Fwiki%2FLe_avventure_d%2527Alice_nel_paese_delle_meraviglie
Compare: https://www.google.com/webmasters/tools/richsnippets?q=https%3A%2F%2Fcommons.wikimedia.org%2Fwiki%2FFile%3AOenothera_rubricaulis_2014_G1.jpg

Just make all those damned templates output something useful in the HTML!

Nemo