their collections. Citation analysis and tools Through its "cited by" feature, Google Scholar provides access to abstracts of articles that have cited the article being viewed. It is this feature in particular that provides the citation indexing previously only found in CiteSeer, Scopus, and Web of Science. Google Scholar also provides links so that citations can be either copied in various formats or imported into user-chosen reference managers such as Zotero. "Scholar Citations profiles" are public author profiles that are editable by authors themselves. Individuals, logging on through a Google account with a bona fide address usually linked to an academic institution, can now create their own page giving their fields of interest and citations. Google Scholar automatically calculates and displays the individual's total citation count, h-index, and i10-index. According to Google, "three-quarters of Scholar search results pages ... show links to the authors' public profiles" as of August 2014. Related articles Through its "Related articles" feature, Google Scholar presents a list of closely related articles, ranked primarily by how similar these articles are to the original result, but also taking into account the relevance of each paper. US legal case database Google Scholar's legal database of US cases is extensive. Users can search and read published opinions of US state appellate and supreme court cases since 1950, US federal district, appellate, tax, and bankruptcy courts since 1923 and US Supreme Court cases since 1791. Google Scholar embeds clickable citation links within the case and the How Cited tab allows lawyers to research prior case law and the subsequent citations to the court decision. Ranking algorithm While most academic databases and search engines allow users to select one factor (e.g. relevance, citation counts, or publication date) to rank results, Google Scholar ranks results with a combined ranking algorithm in a "way researchers do, weighing the full text of each article, the author, the publication in which the article appears, and how often the piece has been cited in other scholarly literature". Research has shown that Google Scholar puts high weight especially on citation counts, as well as words included in a document's title. In searches by author or year, the first search results are often highly cited articles, as the number of citations is highly determinant, whereas in keyword searches the number of citations is probably the factor with the most weight, but other factors also participate. Limitations and criticism