DOI numbers are permanent electronic identifiers for journal articles and other materials published electronically on the Internet. By attaching a DOI number to an article, a permanent and easily findable URL on the Internet is guaranteed, even if the traditional URL changes. Publishers of academic journals can apply for a DOI number for articles in their journals through the library by filling out a form . It is recommended that publishers apply for a DOI number just before the publication of a new issue. Note that all information about the article must be available, as well as a link to each article. Further information johann.h.arnason@landsbokasafn.is