What are ISSN and ISBN?

Every publication needs a reliable identifier.  A single title is not enough, given that the number of publications is growing and they often have similar titles.

The main journal identifier is called International Standard Serial Number.  ISSN is a sequence of 8 characters: the first 7 are digits and the last one is a number or letter X. ISSN is not assigned to each individual issue, but to the whole journal at once. It is assigned once and does not change from issue to issue. At the same time, if periodicals are issued in different formats (paper and electronic), separate numbers are assigned to each version.

International Standard Book Number is a unique number of a book edition. In printed versions it is placed either on the title page or on the back, with a barcode next to it. A book in electronic and printed form will have different identifiers. ISBN is mandatory for all books published through a publisher. If a book does not have a personal identifier, it is not considered an official publication.