search results, and authors are assigned to wrong papers, which leads to erroneous additional search results. Some search results are even given without any comprehensible reason. Google Scholar is vulnerable to spam. Researchers from the University of California, Berkeley and Otto-von-Guericke University Magdeburg demonstrated that citation counts on Google Scholar can be manipulated and complete non-sense articles created with SCIgen were indexed within Google Scholar. These researchers concluded that citation counts from Google Scholar should be used with care, especially when used to calculate performance metrics such as the h-index or impact factor, which is in itself a poor predictor of article quality. Google Scholar started computing an h-index in 2012 with the advent of individual Scholar pages. Several downstream packages like Harzing's Publish or Perish also use its data. The practicality of manipulating h-index calculators by spoofing Google Scholar was demonstrated in 2010 by Cyril Labbe from Joseph Fourier University, who managed to rank "Ike Antkare" ahead of Albert Einstein by means of a large set of SCIgen-produced documents citing each other (effectively an academic link farm). As of 2010, Google Scholar was not able to shepardize case law, as Lexis could. Unlike other indexes of academic work such as Scopus and Web of Science, Google Scholar does not maintain an Application Programming Interface that may be used to automate data retrieval. Use of web scrapers to obtain the contents of search results is also severely restricted by the implementation of CAPTCHAs. Google Scholar does not display or export Digital Object Identifiers (DOIs), a de facto standard implemented by all major academic publishers to uniquely identify and refer to individual pieces of academic work. Search engine optimization for Google Scholar Search engine optimization (SEO) for traditional web search engines such as Google has been popular for many years. For several years, SEO has also been applied to academic search engines such as Google Scholar. SEO for academic articles is also called "academic search engine optimization" (ASEO) and defined as "the creation, publication, and modification of scholarly literature in a way that makes it easier for academic search engines to both crawl it and index it". ASEO has been adopted by several organizations, among them Elsevier, OpenScience, Mendeley, and SAGE Publishing, to optimize their articles' rankings in Google Scholar. ASEO has negatives. See also Bibliometrics List of academic databases and search engines Open-access repository References Further reading Jensenius, F., Htun,