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Library of
Congress Subject Headings
Librarians have different concepts to
describe the two different "types" of
keywords that people search for in databases and catalogs. We call those
searching keywords
either . . .
controlled vocabulary
or uncontrolled vocabulary
We have already introduced you to
uncontrolled vocabulary in Session 1, about using search engines on the
web. There, you had to do a good job of guessing what
terminology the authors of web pages had used in talking about some topic
you were interested in finding. The vocabulary that they used (and
the search terms that you used) were not controlled by any external
standards. If an author of one web page called them cats, and the
author of another web site called them felines, you would have to know
about the use of both of those terms in order to retrieve all of the
documents "about" cats or felines.
Controlled vocabulary keywords are words and
phrases that are the "official" vocabulary of a database or catalog--any online database of bibliographic records
(in indexing service, an abstracting service, a catalog, etc.).
When you search in OU Libraries' online catalog ( which used to be called WebCat,
by the way) using the catalog's "subject" field, you are
actually searching for terms that come from the official controlled
vocabulary (subject headings)
applied to each record by the catalogers in the OU Libraries system. Those subject headings are not just made up
at the time a book is acquired by the OU Libraries system and processed to
be placed in the library's catalog and collection. No, the subject headings
that are applied to each book are already listed in an official, printed
directory that comes from the United States' largest
"national" library, the Library of Congress. In other words, the
choice of the use of a particular subject heading is controlled
by its having been listed in the official list of subject headings
used by the library.
Most academic libraries in the United
States, as well as most other large research libraries, use the system of subject
headings that was originally maintained by the Library of Congress for use
with its
own huge collection.
The name of the system, Library of Congress Subject Headings, is
also known by its initialism, LCSH.
There are other vocabulary control devices
used in other databases. In fact, many of the indexing
services and abstracting services you have known about and used in your
academic career have their own separate "controlled vocabulary" lists.
Psychological Abstracts, Sociological Abstracts,
ERIC: all use different controlled vocabulary lists.
But, the main, most-frequently used list of subject headings (for a huge,
broad variety of indexing services and catalogs) is LCSH.
One of the largest vendors of online
database services, for example, is the service called
FirstSearch. As you will see, it supplies a large number
of the indexing and abstracting services made available through OU
Libraries online. Here is what the FirstSearch system
says about subject headings, and how they allow their users to have access
to them:
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Click the
Subjects
icon to browse the list of subject headings. This feature is useful
when you need to refine the search terms you have chosen or when you
are looking for alternative search terms to broaden the scope of
your search. Use Subjects
to
browse for subject headings based on a term or concept. For an
alphabetical list of subject headings, use the Index
feature. |
FirstSearch doesn't
just make the Subjects icon (this symbol
) available to you in every one of its databases: only some of the
FirstSearch databases have official, controlled vocabulary.
Also, FirstSearch doesn't
show you the Subjects icon immediately after you have entered these
databases. You see, FirstSearch assumes that, by
default, most users wish to use the easiest searching condition or
interface, what FirstSearch calls the Basic Search.
In the graphic below, note that by default, the user is taken into the
Basic Search interface:
When you click on Advanced Search,
you are taken to this screen, where you will find the Subjects
button or icon we have been talking about::
Using
WorldCat
to investigate
LC Subject Headings
One of the databases in FirstSearch
(one of OU Libraries' LORA databases)
is a huge combined "catalog" of the holdings of literally thousands of libraries, mainly in
the US, but some around the world as well. It is called
WorldCat, and you search through that combined (union) catalog of
all those libraries using the retrieval features of the
FirstSearch system.
We are introducing the WorldCat
database to you in this session because of a very, very handy feature it
has associated it: the ability to look for Library of Congress Subject
Headings using its "thesaurus" features (the relationships
of subject headings to other subject headings in broader, narrower, or
related ways).
A thesaurus, in library and information
studies terms, is a controlled vocabulary device that shows its users how
official vocabulary words and phrases are associated with other official
words and phrases. So, for example, you might look up the word
"terrorism" to see under what subject headings the LCSH system had determined
were most appropriate
to use.
After having gotten into the WorldCat
database through the OU Libraries'
LORA
subsystem system,
under its list of Databases, you
would then click yourself into its Advanced Search screen, and click on the upper panel's Subject icon
to be taken to a fill-in screen where you could type in a word or phrase
you are thinking about, like "terrorism."
When you click on "Find," the system will
return with this display for the word "terrorism"
What the system returns with is the word,
which happens to be an official LC subject heading (it doesn't have to be,
though!). We can tell that
because there is a note that says the word is used for other words
or phrases. So, for example, had you tried to look up the subject phrase
"terrorist acts," it would have said to you to use terrorism).
What you need to notice is the link to
Expand
the subject heading "terrorism." In order to find out if there any
broader subject headings or other related or narrower subject headings to the one you
are looking at, you will click on the Expand link:
Here you are told how other official
subject headings are related to the subject heading "terrorism."
If you notice, you are also told you can expand each of these, to roam
around even further in figuring out which official subject headings are
the ones you wish to use to find the materials you are interested in.
Using
OU's catalog
(which used to be called "WebCat")
to Investigate LC Subject Headings
The
library catalog that you will probably be using more frequently than WorldCat
in your future searching beyond this present class, though, is OU's catalog.
This catalog also allows you to find
information about the relationship of subject words to other subject
words, although in a different way. Below, for example, is the same
search (to look up the word "terrorism") in the OU
catalog.
What you are looking for are those entries
found by clicking on this "see related headings for:
TERRORISM"
When you do click through, you get a list
of subject cross references:
As you can see, you will find some of the
same
information using this technique in the OU catalog that was in the WorldCat
system, but please remember that OU Libraries is not likely to have as much information,
because it doesn't have all of the items found in the WorldCat
union catalog of all those thousands of libraries. However, you now know how to find
LCSH information in both
OU's catalog, as well as the larger set of libraries' holdings
(which includes OU, by the way) shown in the FirstSearch
database, WorldCat.
Library of Congress
Classification
One of the things that
all library patrons find helpful is browsing the
shelves around an item they have already located which
turns out to be helpful to their information-seeking.
In fact, the strategy of shelf browsing is so helpful
that the American Psychology Association, back in the
1970's, came up with a name for it (and other similar
searching behaviors), when a set of reports they did
surveying the searching/finding behavior of American
psychologists (who were members of the APA) identified
it as what the researchers called "library
serendipity." It meant finding something
accidentally ("discovering" something) that was
physically close to what you already knew about and
were looking for.
Of course, library
classification schemes (Library of Congress, Dewey
Decimal system, etc.) are intended to do exactly that
for the patron who walks to the shelves to find the
book he or she is specifically looking for:
classification schemes seek to put like books
together, or close to one another, on the shelves.
What do we do, though,
when we are doing our searching through an online
catalog that is available to us from anywhere in the
world we happen to be located? Well, we can still
browse the library's book shelves, but we have to do
it through the online catalog that the library makes
available to us.
We are going to show
you two different ways in which you can browse the
shelves of the OU library's book stacks through its
online catalog. Even better, we are going to indicate
to you that you should use this technique, even if you
were actually starting at the front entrance of the OU
Bizzell library!
Why? Because a lot of the more
in-demand books are already checked out of the library
by someone else, so you wouldn't see those titles were
you to rely on browsing the actual shelves. Let us
say that again: it is sometimes almost BETTER if you do your
shelf browsing online, because you are shown
information about ALL of the titles that would have
been on the shelves if they hadn't been checked out by
someone else (Thomas Mann makes essentially the same
point when he complains that faculty typically are
given longer loan periods on books that tend to keep them off the
shelves when others might be looking for them, or
other books like them. Dr Bob agrees with him about
that too: he used to ask his LIS students,
rhetorically, why it took an undergraduate two weeks
to read a book, but a faculty needed one year to read
the same thing!)
Conceptually, the
ability to browse (virtually) a library's collection
is known as looking through its "shelf list." What is
a shelf list? It is a file of all of the books in a
library's collection, arranged in call number order;
doesn't matter that some of them are checked out of
the library by patrons, because the shelf list
included all the books that are officially "in" the
collection. That is exactly what you are given by
OU's Webcat (the OU library online
catalog) when you ask to "browse" it by call number.
1. Finding a
particular book's call number in
Webcat,
and browsing forward and backward from it
Lets say we are
interested, again, in the book by Jared Diamond called
Guns, Germs, and Steel. Well, what
you could do is simply search for his book in the
catalog, and having found it, use its call number to
"browser the shelves" after it. So, lets say you
know that Diamond's book has the call number HM
206.D48 1997.
Well, the first thing
you want to do is get into the catalog's Advanced
Search area:
Once there, click on
the label on the right that lets you request a "Call
Number" search:
On that next screen,
type in the call number you have previously found for
Diamond's book (I typed in "hm 206.d48", as you can
see below). Then click the Search button.
As you can see below,
that returns a list of books, in call number order
that occur on the shelves of the OU library collection
AFTER the call number you typed in. Obviously,
to go the other way (call numbers BEFORE this one, you
would have to click on the Previous label
above.
Now you know how to
find out what books are "around" a book you already
know about: you find that book in the OU catalog
and then use its call number to "browse" the
list of books that are in the collection.
2. Overview
of the LC Classification system
There are several good
resources for detailed tables showing what topics are
where in the LC Classification system. One of them is
a set of pdf files from the Library of Congress
itself; the other is a set of pages found at About.com:
And please don't forget
that if you have access to the printed LCSH,
it will give you classification areas that are related
to the subject headings you are looking up. If
you are a member of the US military, please ask your
local military library staff if they have a copy of
the LCSH for you to use.
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