doi.org
A digital object identifier (DOI) is a persistent identifier or handle used to uniquely identify various objects, standardized by the International Organization for Standardization (ISO). DOIs are an implementation of the Handle System; they also fit within the URI system (Uniform Resource Identifier). They are widely used to identify academic, professional, and government information, such as journal articles, research reports, data sets, and official publications. DOIs have also been used to identify other types of information resources, such as commercial videos. More information...
According to PR-model, doi.org is ranked 2nd in multilingual Wikipedia, in particular this website is ranked 2nd in English Wikipedia.
The website is placed before books.google.com and after web.archive.org in the BestRef global ranking of the most important sources of Wikipedia.