Citation index
A citation index is an index of citations
between publications, allowing the user to
easily establish which later documents cite
which earlier documents.
The first citation indices were legal citat-
ors such as Shepard’s Citations (1873). In
1960, Eugene Garfield’s Institute for Scientif-
ic Information (ISI) introduced the first cita-
tion index for papers published in academic
journals, starting with the Science Citation
Index (SCI), and later expanding to produce
the Social Sciences Citation Index (SSCI) and
the Arts and Humanities Citation Index
(AHCI). As of 2006, there are other sources
of such data, such as Google Scholar.
Major current citation in-
dexing services
There are two publishers of general-purpose
academic citation indexes, available to librar-
ies by subscription:
• ISI is now part of Thomson Scientific.
Though the ISI citation indexes are still
published in print and compact disc, they
are now generally accessed through the
Web under the name Web of Science,
which is in turn part of the group of
databases in WoK.
• Elsevier publishes Scopus, available online
only, which similarly combines subject
searching with citation browsing and
tracking in the sciences and social
sciences.
There are a number of other indexes, more
readily available. Some of the currently not-
able ones are:
• The CiteSeerX system provides citation
and other searching of scientific
literature, primarily in the fields of
computer and information science[1]
• RePec provides this in economics, and
other discipline-specific indexes have also
begun to include it in their indexes. Even
journal publishers often supply the facility
to link to late citations, at least from the
journals they publish.
• Google Scholar (GS) has citation
functionality, limited to the recent articles
that are included. There is already
discussion about the possibility that GS
may in the future have sufficient
capabilities to make the commercial
products unnecessary.
Each of these products offer an index of cita-
tions between publications