As I mentioned in my previous posts, the entitization of publishers was only recently problematized when the new BibFrame model was proposed, which treats publishers as a separate entity in the overall bibliographic universe, rather than a text string in the MARC record. However, from the perspective of cataloging, we still do not seem to know too much about what a publisher is.
In the MARC record, two fields, 260 and 264, are used for describing information about the publication, printing, distribution, issue, release, or production of the resource. The use of these two fields are different in the two cataloging rules, AACR2 (The Anglo-American Cataloging Rules, 2nd edition) and RDA (Resource Description and Access) that replaces AACR2. In the period of AACR2, all publisher and distributor information should be described in 260 subfield b, where multiple subfields can be used when there are more than one publishers/distributors. In the RDA rules, however, the 264 field should be used and different functions (primarily publication and distribution in the previous context) are distinguished by the second indicator of this field. One of the issues with the AACR2 rules is that it does not require publisher names to be transcribed just as what is displayed in the resource: catalogers have the freedom to omit or abbreviate some name components, such as “publishers” and “limited.” In certain ways, the RDA rules is more consistent with how publishers are supposed to be dealt with in a more modern information infrastructure: that publishers should be recorded in more consistent and structure manners and not mixing with other types of entities (especially distributors but also printers and issuers). But in practice, the majority of library bibliographic records were produced under AACRS rules, which are almost impossible to be transformed into RDA rules because we do not know what name components were omitted or abbreviated.
While how publisher names are described (inconsistently) in the MARC format is just one barrier to the identification of publishers that is relatively easy to solve, a real challenge in the present project is the history of the publishing industry. In the real-world context, what is described in 260/264 subfield b is just an imprint, which, by definition, is the unit that publishes, no matter what the unit is (it could be a publisher, or a brand or branch that is owned by the publisher, or an individual person that publishes the resource). For example, in this link, you can see all imprints that are owned by Penguin Random House, which BTW, was merged from Penguin Group and Random House in 2013, two of the largest publishers in the American publishing market.
Throughout the history of the publishing industry, publishers have been merging and splitting, just like the example of Penguin Random House. They might acquire a different publisher in total, or just some brands (imprints) owned by another publisher. And in some rare cases, an imprint was sold to a different publisher but was sold back to its original owner later. Shown below is a slice of data manually collected by Cecilia about the history of Wiley, another major publisher in America.
[A slice of the history of Wiley]
From this imprint-centered view, a publisher is a higher level entity than imprints that includes all its child entities in a given time. In other words, quite unlike other bibliographic concepts, such as works (“great works are timeless”), publishers or imprints exist in a temporal framework. But this is a huge challenge for this project, partly because the idea of temporality is extremely difficult to be combined with network analysis methods. While I cannot give any solution at this time for this difficulty, this will be an interesting topic to be further addressed in my works.