Reference Services and Sources

The function of libraries is three-fold. Libraries acquire information, organize that information in a way it can be retrieved, and disseminate the information it has acquired. Reference services fulfill this last function. Reference services may vary from library to library, but most libraries have an information or Reference Desk where assistance from a librarian is available. Almost all libraries also provide reference services via the telephone and in many libraries you can email your reference question, or ask a Librarian, to a reference librarian who will e-mail you back with the answers.

There are three main types of reference assistance:

  • Assistance or instruction in the use of the library, including location of materials, use of the catalog, use of computers to access information, and the use of basic reference sources.
  • Assistance in identifying library materials should include answering questions.
  • Providing brief, factual answers to questions, such as addresses, statistics, phone numbers, etc. that can be quickly located.

Reference Sources

Reference sources such as dictionaries, encyclopedias, almanacs, atlases, etc. are research tools that can help you with your paper or project. Reference sources provide answers to specific questions, such as brief facts, statistics, and technical instructions; provide background information; or direct you to additional information sources. In most libraries, reference sources do not circulate and are located in a separate reference collection. This practice makes reference sources readily available and easily accessible.

Reference sources are designed to be consulted rather than read through. Their design is generally dependent on the type of information and treatment provided. Reference materials can be arranged alphabetically, topically, or chronologically. Many will contain cross-listed information and more than one index. If it is not obvious how a reference source is organized, take a moment to look through the explanatory or how-to-use information, which is usually presented at the beginning of the book.

There are thousands of reference sources available that cover practically every subject. Although the term reference “book” is frequently used, reference sources can be books, serials, online databases or the Internet. A large part of using reference sources well is choosing the right one.

Despite the wide variety available, reference sources can be categorized into a handful of groups. Think about the kind of information you need and how you will use it. If you are unsure which reference tool is best suited to your information need, a reference librarian will be able to assist you.

Quick guide for selecting the right type of reference source

For information about… Choose…
Words Dictionaries
General information/Overview of topic Encyclopedias
Names & addresses of people, organizations, institutions, companies Directories
Profiles of people Biographical Dictionaries
Places/Maps Gazetteers or Atlases
Facts and Statistics Almanacs
Formula, Tables, How-To-Do-It Handbooks and Manuals
A person’s work Reviews or Criticisms
Dates, outlines, historical timelines Historical tables, Chronologies, Historical yearbooks
Periodical Articles Indexes or Abstracts
Books and other sources Bibliographies or Guides to Literature…

Types of Reference Tools

Two major categories of reference materials are general and subject. General sources include all subjects and present overviews of topics. Reference materials focused on specific subjects can provide more in-depth coverage.

There are reference sources that provide information on specific subjects as well as general sources that provide information on many subjects.

In general, reference sources are either general or subject specific. If you need an overview of a subject, perhaps a general information source will suit your needs. If you need specialized information, a subject specific tool may be better suited.

The following reference sources and others are available in the main Reference Collection of IES library.


Dictionaries provide information about words.

  • General dictionaries are the most familiar to us. You may even own one. This group includes Webster’s International Dictionary, the Random House Dictionary of the English Language, and the Merriam-Webster Collegiate Dictionary. These sources generally provide definitions, pronunciations, syllabication, and usage.
  • Historical dictionaries provide the history of a word from its introduction into the language to the present. The Oxford English Dictionary is an excellent example of this type of dictionary.
  • Etymological dictionaries are dictionaries which emphasize the analysis of components of words and their cognates in other languages. These dictionaries emphasize the linguistic and grammatical history of the word usage. The Oxford Dictionary of English Etymology is an example of an etymological dictionary.
  • Period or scholarly specialized dictionaries focus on a particular place or time period.
  • Foreign language dictionaries are fairly self-explanatory. We’ve all looked up words in French, German, Spanish or other Western European language.
  • Other continents countries’ language dictionaries.
  • Subject dictionaries focus on word definitions in a subject area.
  • Other dictionaries include dictionaries of slang, abbreviations, synonyms, antonyms, abbreviations, acronyms, reversals, rhyming, idioms, phrases, and guides to correct usage. Dictionary of Acronyms and Abbreviations. Dictionaries, like other reference sources, may belong to more than one category.

Dictionaries may be abridged or unabridged. Abridged dictionaries are smaller and contain the most commonly used words. Unabridged dictionaries try to include all words in current usage. Like other reference sources, dictionaries may become outdated as language evolves. Care should be taken to carefully identify the publication date and focus of the dictionary selected.


Encyclopedias provide general background information; they are a good place to start researching a topic that you know little about. Large subject areas or disciplines are covered in broad articles that explain basic concepts. These overview articles often contain references to more specific aspects of the larger topic and may include a bibliography that leads you to more in-depth sources. Encyclopedias may be general or subject specific.

  • General encyclopedias usually arrange articles alphabetically by topic. Look for an accompanying index which may list cross-references to other articles. Included in this category are Encyclopedia Britannica (29 volumes), The Cambridge Encyclopedia, Encyclopedia Americana, and the Columbia Encyclopedia.
  • Subject encyclopedias are available for almost every academic discipline. They provide more in-depth and technical information than general encyclopedias. Subject encyclopedias generally assume some prior knowledge of the subject. There is no general rule for how these tools are arranged.


Directories provide names, addresses, affiliations, etc. of people, organizations, or institutions. They can be used to verify addresses, name spellings, and provide contact information. As in other reference sources, directories may be general or focused on a particular subject.

Biographical Dictionaries

Biographical dictionaries contain short articles about people’s lives.

Gazetteers or Atlases

Geographic information is located in gazetteers, atlases and maps.


Contain collections of maps. They provide information on geographical/political changes. There are world, national, and thematic atlases and these may be current or historical.


Almanacs contain statistics and facts about countries, events, personalities, or subjects.


Handbooks and manuals are subject area tools. Handbooks provide facts, terms, concepts, movements, etc. of a topic. Manuals provide detailed instructions on a particular subject, such as how-to-do something or how something works.

Review and Criticism Sources

These tools provide reviews or critiques of a person’s work.

Historical Tables, Chronologies, Historical Yearbooks

Historical tables and chronologies present historical facts in different formats. Historical tables provide facts chronologically in columns with each column representing another geographical area or other major area, such as history, economics, and religions. Chronologies use narrative form to present facts. Historical tables and chronologies may span long or very short time periods. Historical yearbooks provide facts and statistics for a single year and may be published annually.

Indexes and Abstracts

Indexes and abstracts lead to additional sources of periodical articles. Indexes only provide author, title, and subject information. Abstracts tend to be more descriptive. Some online index databases also include the full-text of the article.


Bibliographies lead to other information sources. They are lists of books and other materials that provide author, title, and publication information. Annotated bibliographies also include a brief description or summary of the item. Bibliographies are available on almost every topic and may focus on specific persons, groups, subjects, or time periods. Many bibliographies are selective and do not attempt to include all publications. Bibliographies are sometimes referred to as “Guides to the Literature …”

Ready Reference

The Ready Reference Collection contains reference sources that are used most frequently. The Ready Reference shelves are always located adjacent to the Reference Desk.