Gelman library or by its full name the "Estelle and Melvin Gelman Library", is one of the many GLAMs we have content from in Commons. For all these institutions there is a template in the "Institutions" namespace.
All these templates are an amazing resource, it must have been compiled by many people over many years. On Commons it links to material that is known to be part of the collection of that institution. Making such links is in itself an Herculean job and one that is not finished at all.
The template on all those institutions typically refer to a Wikipedia article. The Wikipedia article links to a Wikidata item and it aims to include all the information that exists on the institution template on Commons. To harvest all that information tools like the pywikipedia bot will be used.
Some people complain about Wikipedia that "everything is said and done". For those people Wikidata is a bit of fresh air; there is so much more that can be done.