Every month, more search engines are offering the option of cited reference searching. This powerful but, traditionally, expensive feature shows newer articles that have cited an earlier publication.
This uniquely handy tool for researchers can be used to:
- Identify updated information on a relevant but dated article.
- Explore additional applications for tools or protocols.
- Provide authors with a measure of the impact of their work. It has been used for this purpose in both visa and promotion applications.
- Help finding a job; by identifying which labs have cited work in which you were involved.
- Trace the development of an idea over time.
Cited reference searching was first developed in the legal field, which builds arguments by referring to earlier interpretations of law. The most famous provider of academic cited reference searching is ISI, which produces the Science Citation Index, Social Sciences Citation Index and Arts & Humanities Citation Index along with their more recent online equivalents, the Web of Science and the Web of Knowledge.
In 1998, autonomous citation indexing, which automatically extracts citations and their context from text, was developed. This and other technological innovations have led to widespread availability of cited reference capabilities. We'll look briefly at some of the JEFFLINE options for cited reference searching, including Scopus, Google Scholar, Ovid databases including special CINAHL and PsycINFO citation searching features, HighWire Press, PubMed and Amazon.
But first, what should the savvy researcher know when choosing a database for cited reference searching? To put your search results in perspective (particularly for tenure and promotion purposes), you should know:
- Does the database provide citations to all articles or just those indexed in the database?
- Is there a measure of control to group variations of the citation in different articles, accounting for abbreviated vs. full journal titles, variations in author initials, etc.?
- For what time period are cited references available in the database? For example, the database may have citations back to the 1800s but only have cited references for a few decades (as does Scopus). How recent are the most up-to-date citations in the database (is there a lag between publication time and the citation's entry in the database)?
- What is the breadth of publications in the database? What subject matters are covered, how many journals are indexed, are they indexed in full? Does the database include all of the publications in your area of expertise? Does it cover international and non-English language publications, does it provide cited references for publication types other than journal articles, such as book chapters? Does it search only publications which that publisher offers (as does Ovid citation searching and some of the vendor platforms)?
Other cautions about interpreting the importance of often-cited articles include the possibility that an article is cited because it is a review, describes a commonly-used protocol, is older and has accumulated more citations over time, or is a notorious example of bad science! The best citation-analysis packages will allow researchers to remove articles in which authors cite their own earlier work.
Let's briefly examine some of the resources currently available to Jefferson researchers.
Scopus and Web of Science /Science Citation Index
Both Web of Science and Scopus are huge citation databases covering a broad range of subjects. Some researchers have rated Scopus higher than Web of Science for coverage of non-English and foreign journals. Web of Science provides more thorough coverage of the humanities and social sciences.
In studies comparing results of citing reference searching between Web of Science and Scopus, Scott librarians have generally found a similar number of citations in both databases with a few exceptions. These are generally:
- older citations -- Scopus citing references only go back to 1996.
- some extremely recent citations. Although Scopus contains “the entire PubMed database” there is a lag between the entry of records into PubMed and their appearance in Scopus.
While Scott Library does not offer current end-user access to the Web of Knowledge/Web of Science, it does provide CDROMs of the ISI Science Citation database from 1986 to 2003 and print indexes from 1955-1985. Reference librarians can perform searches of the Web of Science for years other than these for a fee.
Scopus is available on JEFFLINE. Each Scopus citation includes a link to any articles citing it. It is also possible to identify articles that cite an article that does not appear in Scopus, by searching in the References field. Scopus also indicates on a separate tab which patents have cited a given article.
For tracking citations by a given author, Scopus provides authority control features that help to account for variations in author names. It also provides Citation Tracker, a sophisticated tool for analyzing impact of publications.
Results of searches from the Author Search tab link to a list of authors and their affiliated institutions, so the searcher can choose the correct author from those with similar names. Results of articles citing that author will allow you to remove author self citations.
The Scopus Citation Tracker can be used to identify citations by a given author or institution, or those on a topic. After choosing articles to track from the results of preliminary search by author, affiliation or subject, the link to Citation Tracker will present a chart of the number of times each publication has been cited each year. Results can be sorted by year, or number of times cited, etc.
Scopus also provides a feature to “Alert me when this document is cited in Scopus.”
Scopus has announced it will soon add WebCites, which will display in a separate tab websites that cite articles in Scopus. The websites will include institutional repositories, thesis and dissertation databases, and other carefully selected scientific web sources.
GoogleScholar
While Google Scholar cited references search is accessible and free, it returns far fewer results than Scopus or Web of Science. Because Google Scholar is still in Beta testing, it is difficult to determine the universe of citations that it is searching. Tests over time find that results are increasing and the interface is increasing in sophistication, so stay tuned.
Ovid, With Special CINAHL and Psycinfo Cited Reference Searching Features
Ovid's Find Citing Articles feature should be called “Find Citing Journals@Ovid Articles.” This feature only identifies citations that appear in any of the several hundred journals in the Journals@Ovid database. These journals only go back to 1993, and are mostly clinical journals.
The Find Citing Articles feature also ignores the cited reference searching features in CINAHL and PsycINFO, which include citations from books and book chapters, as well as journals not found in Journals@Ovid. CINAHL's citations began in 1994 and PsycINFO's go back to 1988.
The more comprehensive (within the subject matter of each database) cited articles feature in CINAHL or PsycInfo, is used by choosing the More Fields link from the main search page and choosing the References field (.rf.).
Enter search terms using adjacency features, e.g. Crick adj10 helix. In the More Fields window, PsycInfo offers the ability to search specific parts of the Reference field such as author, publisher, title, source, etc.
HighWire Press
HighWire Press is the common interface for many society journals. Its “Articles Citing this Article” feature formerly used ISI Web of Science. It now uses Google Scholar. Special features include a citing alert and the Citation Map. “Alert me when this article is cited” will email an alert whenever the article is cited within that same publication or within articles in about 1000 other journals.
The Citation Map graphically represents the citations in a given article and other HighWire-hosted articles citing it, and any citing among these articles. In the expanded view, one can identify which articles in that universe of articles have the greatest impact.
HighWire Press suggests that the Citation Map can help readers develop reading lists to get up to speed on a new topic, generate bulk citation lists for import into literature-management programs, and assist in refereeing or writing a review article.
PubMed
PubMed results offer the opportunity to see citations for a given article in other articles in PubMed Central and in NCBI Bookshelf books. From the search results, choose the pull down display options for either Cited in PMC or Cited in Books.
Amazon
Amazon offers the ability to search for citations using the Amazon "search within a book" feature. This is a very crude and non-comprehensive search feature, but it does offer Jeffersonians a rare ability to identify citations in books in fields other than psychiatry and nursing.
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