Every work registered under a DOI prefix, ranked by the number of citations received — from most to least cited.
From the is-referenced-by-count field of the Crossref API, which counts citations registered among members participating in Cited-by.
Google Scholar crawls the web and includes theses, preprints and other documents; Crossref counts only formally registered citations. Scholar numbers are usually higher.
Yes. After the query, use the publication year selector to narrow the list.