In the last few years the use of electronic sources, according to the development of information technology. has become increasingly necessary. But, there is nobody who checks the reliability of information found on the Web, CD-ROMs, online databases. Usenet Newsgroups or electronic journals because it is easily modified in any time and users may not always access the same sources. So, when citing those electronic sources, it is necessary to provide a proper bibliographic citation which enables readers to identify and obtain the work. Although, until today, any bibliographic format is not uniformed yet. This paper briefs the history of the international efforts for the standardization of the bibliographic references for electronics sources. And then, this article deals with the prescript based on ISO 690-2 as the reasonable solution for citing electronic sources, describing the basic specifications for data elements and their prescribed order. The author also describes the Spanish form on the above mentioned bibliographic format and discusses several problems associated with it.