Library Catalog Searching

Searching catalogs is the key to finding library resources. Long before computers, catalogs were developed to organize and retrieve materials. Catalogs follow well-defined subject hierarchy and classification systems. Most catalogs are now online so you can find materials on your topic almost anywhere in the world. An online public access catalog is called an OPAC.

The online catalog is used primarily to search for book titles. Many catalogs also include journal and magazine titles, as well CDs, DVDs, tapes and video titles. Some libraries have separate specialized collection catalogs that may include manuscripts, pictures, music, maps, newspapers and documents. Like books, these special collections are accessed by author, title and subject. As with books, Web access only finds titles and not the actual content. Although libraries are moving toward providing more content online, few libraries currently have online digitized book collections.

Classification Systems

Classification systems were developed in order to retrieve materials. The system assigns unique subject numbers/or letters to each item. Items on the same or similar subjects are grouped together.

There are two major systems used in the United States. One is the Dewey Decimal system, named for the creator. It assigns a numerical code to the subject and refines the subject by adding more numbers behind decimals. It is used by many public libraries. The other major system is the Library of Congress system. This system uses letters and numbers to assign subject areas. It is based on the alphabet. It also refines the subject by adding letters and numbers separated by decimal points. In both systems, authors are assigned unique numbers as well. It helps identify books by the same author and place them together.

Below is a comparison of the two systems to give you a better idea of how they work:

Searching catalog records

Each catalog record has several fields. The most common fields are author, title, book size and contents, and subject heading. Common searchable fields are author, title and subject. Any given catalog may have additional search fields.

The following examples use the University of California's online catalog called MELVYL, which you can access at: http://www.dbs.cdlib.org/

Try following the examples as we go through them. Open a separate Web browser window and place it side-by-side with this window, so you can easily switch between them. The main MELVYL menu looks like the one below:

Title searching uses the words in the book's title or subtitle. If you know the title, you can use the "exact" search in which each word is matched in the order given.

If you know only some of the words in the title, you can use the "any words" option. Don't use stop words (Common words that are ignored because they would retrieve too many results, such as "a," "an," "and," and "the." Usually they do not affect the meaning of the title.

Using the "any words" option expands your search because all books with these words, in any order, are retrieved.

Author searching is done by the author's name. Usually (but not always), you enter the last name first. If you enter just a last name, the search will retrieve all authors by that last name. If you know the first name or initials, use them. Entering as much of an author's name as possible will save time. Not all materials have just a single author; some may have several or none. Authorless books may have editors or be a collection of material. You can search for these types of books in other ways. For now, here is how a single author search works on MELVYL:

In both the Dewey and Library of Congress systems, subject descriptors are assigned to the book's record in the catalog. Subjects are searchable fields. Try to narrow your subject as much as possible. For example: "breast" is the broad subject and "breast cancer" is the narrower subject. It's a good idea to start your subject searches after you find a good reference source and can then use its subject classifications to find related materials.

Let's use the subject categories we got on the long display a few screens back:

Catalog searching only covers a set collection. However, this collection might be spread over several libraries. If so, a location code is assigned to each library. In our previous example, the University of California MELVYL catalog covers all of UC's libraries. It also includes the California State Library, California Academy of Sciences, California Historical Society, Center for Research Libraries, and the Graduate Theological Union. Your MELVYL search covers all these libraries with more than 9 million unique titles representing more than 13.8 million holdings! Not bad for letting your fingers do the walking.

In the California Community College and California State University systems, each district has its own catalog and must be searched individually. Check your local campus library.

Some library online catalogs will give you more options for searching though subject categories than were provided using MELVYL. The following examples are from the Santa Rosa OPAC at http://www.santarosa.edu/library/catalog.shtml.

To follow along, use the Web interface from a home computer setting, click on http://198.189.142.246/model2a.html and select a new search.

Getting the Material

Some library material you find through an online catalog can't be checked out. However, most can and are available through your local library by the Interlibrary Loan. Ask your library about process and fees. Delivery time varies.