I see that Catalogo Vegetti della Letteratura Fantastica (beta) is a large online and public bibliography of 1,444 works, published in Italian, by and about Howard Phillips Lovecraft. It also has smaller bibliographies for Robert E. Howard, Bradbury, Clarke, and others in Italy.

They also have a call for contributors, though Andrea Bonazzi states (see comments, below this post) that it hasn’t been updated since 2010 when its author passed away. Looks like it could do with some new contributors, to update with 2009-2019. That would be a nice addition to the C.V. of some aspiring young cataloguer, and (in Italian) it shouldn’t be too big of a job.

It’s presented under the auspices of the Cataloguers’ Guild of Italy, and the newer Catalogo is a CC-Attribution continuation of Vegetti’s older Catalogo della Fantascienza, Fantasy e Horror.