The meaning of the 'impact factor' in the case of an open-access journal

Fifty years ago, when computers were a rarity, librarians used index cards to keep records of library holdings. The cards were arranged into an author index and a subject index. To find publications related to the subject of his or her research, a researcher went to the subject index, drew the box with the cards on the subject, look at the long row of cards, and did not know where to start. Since the cards were ordered alphabetically, the seminal works on the subject were lost in the mass of less important publications.Pointing out that subject indexes were "limited in their attempt to provide an ideal key to the literature", Eugene Garfield proposed, in 1955, a new bibliographic tool -- a "citation index"[1]. The underlying idea of this tool may be formulated as follows. A seminal work could be an ideal key to the literature on the subject to which it gives the birth, if all the references to this work were to be listed on its card (see details in Appendix).In 1960, Garfield founded the Institute for Scientific Information (ISI), and started a bibliographic indexing service-the Scientific Citation Index, which has been continued since 1992 by the Thomson Reuters Corporation.In 1975, ISI began to publish Journal Citation Reports (JCR), which became later "the recognized authority for evaluating journals" [2]. The logic of journal evaluation was developed by Garfield [3] at the time when there were no open-access journals, and nobody has assessed yet whether the logic of counting citations is able to cope with this modern reality.The JCR summarizes citation data and delivers detailed reports that are supposed to be helpful for librarians, authors, editors, publishers and administrators [2]. The most known metric provided by the JCR is the journal impact factor: the ratio of the current year citations to the source items published in the journal during the previous two years. The following four examples are to show how it may help librarians, authors, editors and publ