query: #defaultView:ImageGrid
  SELECT DISTINCT ?library ?libraryLabel (SAMPLE(?image) AS ?image) ?sitelinks WHERE {
  ?library wdt:P31/wdt:P279* wd:Q7075 . # libraries or subtypes
  MINUS {?library wdt:P31/wdt:P279* wd:Q212805} # but not digital libraries
  ?library wikibase:sitelinks ?sitelinks.
  OPTIONAL {?library wdt:P18 ?img}
  BIND (IF(BOUND(?img), ?img, <http://commons.wikimedia.org/wiki/Special:FilePath/No image available.svg>) AS ?image)
  SERVICE wikibase:label { bd:serviceParam wikibase:language "[AUTO_LANGUAGE],en" }
  } GROUP BY ?library ?libraryLabel ?sitelinks
  ORDER BY DESC(?sitelinks)
  LIMIT 1000