The possibility of using different IDs for digital publications, periodicals, and personal identifiers for scientists who are used to facilitate the retrieval of information in electronic global array of scientific content is examined. The outlook of the International Publishers Association PILA (Publishers International Linking Association, Inc.), which coordinates the work of the CrossRef Agency is provided. The function of this agency is managing and supporting of the information database of digital object identifiers (DOI's). The definition of digital object identifiers (DOI's) and their work features is given. The procedure of assigning DOI's to scientific publications and other objects is described. The opportunities of Crossref search interface and the main advantages of Crossref system are shown.