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Reference Services and Sources

Learn about: Reference services, types of reference sources, where and how to find reference sources.

Reference Services

The function of libraries is three-fold. Libraries acquire information, organize that information in a way it can be retrieved, and disseminate the information the library has acquired. Reference services fulfills 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 provide reference services via the telephone and many libraries offer email, text, or chat services with a reference librarian.

There are three main types of reference assistance:

  • Assistance or instruction with using the library, including locating materials, using the catalog, using computers to access information, and using basic reference sources.
  • Assistance identifying library materials needed to answer a question.
  • Providing brief, factual answers to questions, such as addresses, statistics, phone numbers, etc. that can be quickly located.

Types of 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. Reference sources are not scholarly (peer-reviewed). 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. 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, or in HELP screens for online products.

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, on-line databases or information found on the Internet. A large part of using reference sources well is choosing the right one for your needs.

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 (Collins, 151):

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 reference sources include all subjects and present overviews of topics. Subjects specific reference sources provide in-depth coverage on specialized topics.


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 anaylsis 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. For example, try the Dictionary of Alaskan English if you would like to know when the word "cheechako" was first used.
  • Foreign language dictionaries are fairly self-explanatory. We've all looked up words in a French or Spanish or other Western European language. Don't forget other wonderful dictionaries, such as the Yup'ik Eskimo Dictionary or the Inupiat Eskimo dictionary.
  • Subject dictionaries focus on word definitions in a subject area, such as finance, law, botany, electronics, physics, etc.
  • Other dictionaries include dictionaries of slang, abrreviations, synonyms, antonyms, abbreviations, acronyms, reversals, rhyming, idioms, phrases, and guides to correct usage. Dictionary of Acronyms and Abbreviations, The Macmillan Dictionary of Historical Slang, Roget's II: The New Thesaurus, The American Language, Strunk's Elements of Style.

Dictionaries, like other reference sources, may belong to more than one category. For example, an English-Russian engineering dictionary is both a foreign language and a subject dictionary.

Dictionaries may be abridged or unabridged. Abridged dictionaries are smaller and contained 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. General dictionaries begin with LC call numbers starting with AG. Specialized dictionaries will have subject specific call numbers.


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 Encyclopaedia Britannica, The Cambridge Encyclopedia , Encyclopedia Americana, and the Columbia Encyclopedia. General encyclopedia LC call numbers begin with AE.
  • 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. Look for an index. A few examples of subject encyclopedias include the McGraw-Hill Encyclopedia of Science and Technology, International Encyclopedia of the Social Sciences, Encyclopedia of World Art, Encyclopedia of Philosophy, and the Encyclopedia of Archaeology. Subject encyclopedias will have subject specific call numbers.


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. Biography resources have call numbers that begin with CT.

  • General biographical dictionaries include Current Biography, Dictionary of American Biography, Who's Who, Encyclopedia of World Biography, etc.
  • Subject biographical dictionaries may focus on a subject area or group. These sources include Dictionary of Scientific Biography, Contemporary Authors, Biographical Dictionary of Psychology , New Grove Dictionary of Music and Musicians, Women of Science, etc.

Gazetteers or Atlases

Geographic information is located in gazetteers, atlases and maps. Geography resources have call numbers that begin with G.

  • Atlases 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.
    • World atlases include National Geographic Atlas of the World.
    • National atlases: National Atlas of the United States, Atlas of the American Revolution.
    • Thematic atlases focus on a specific subject area, such as astronomy or agriculture. Examples include, The Oxford Economic Atlas of the World and the Environmental Atlas of Alaska.
  • Gazetteers are sometimes referred to as geographical dictionaries and provide descriptions of places, but no maps.
    • General gazetteers include Webster's New Geographical Dictionary, The Columbia Lippincott Gazetteer of the World, Gazetteer of Undersea Features, etc.
    • Regional gazetteers, such as Dictionary of Alaska Place Names, by D. Orth, focus on a specific geographical region and are good places to look if you want to know the location of a town, its population, or where its name came from.

Sometimes atlases and gazetteers are combined, as in the Alaska Atlas and Gazetteer, by DeLorme Mapping, which publishes similar products for the other states.


Almanacs contain statistics and facts about countries, events, personalities, or subjects. Almanac resources have call numbers that begin with AY.

  • General almanacs include the Statistical Abstract of the United States, The New York Public Library Desk Reference, World Almanac (an American focus), Information Please Almanac (print ed. called Time Almanac), Whitaker's Almanak (United Kingdom focus).
  • Subject almanacs include The Weather Almanac, The Almanac of Renewable Energy, Political Reference Almanac, Alaska Almanac, and more.


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.

  • Handbooks: Handbook of North American Indians, Guide to Alaska Trees, Words and Ideas: A Handbook for College Writing, Handbook of Mathematical Formulas, MLA Handbook For Writers of Research Papers.
  • Manuals: Manual of Photography, Manual for Environmental Impact Evaluation, Alaska Craftsman Home Building Manual, United States Government Manual.

Review & Criticism Sources

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

  • General: Book Review Digest, MLA, New York Times Book Review, Contemporary Literary Criticism.
  • Subject: Children's Literature Review, Popular Music Record Reviews.

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, religions. etc. 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.

  • Historical Tables: The Timetables of History, Historical Tables, 58 BC-AD 1985.
  • Chronologies: Chronology of World History, The New York Public Library Book of Chronologies, Chronology of the Expanding World, 1492-1762, A Chronology of the People's Republic of China from October 1, 1949, Annals of European Civilization, 1501-1900.
  • Historical Yearbooks: The Statesman's Year-Book.

Indexes & 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.

  • General: Reader's Guide to Periodic Index, Book Review Index, Periodicals Abstracts.
  • Subject: Art Abstracts, New York Times Index, Biography Index, Chemical Abstracts.


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 ..."

Examples: American Fiction, 1774-1850, Bibliography of Education, Utilization of Wood Residues: An Annotated Bibliography, A Bibliography of Sir Walter Scott, MLA Bibliography, Current Bibliographies in Medicine (NLM), Alutiiq Ethnographic Bibliography (ANKN).

Ready Reference

The Ready Reference Collection contains reference sources that are used most frequently. The Ready Reference shelves are located adjacent to the Reference Desk. The collection includes reference tools such as The Encyclopedia of Associations, The Encyclopedia of Associations, The Dictionary of Alaska Place Names, Style guides (MLA, APA, Chicago), a thesaurus, The Physician's Desk Reference, Alaska phone directories, Black's Law Dictionary, World Almanac, The Merck Manual of Medical Information, Zip Code Directories, etc.

Where to Find Reference Sources

Some of Rasmuson Library's reference books are available in print, but many are available online. For example, Rasmuson Library subscribes to Credo Reference and  Oxford Premium Reference Collection. These databases contain both general and subject specific dictionaries, encyclopedias, almanacs, and other reference material. 

For subject specific reference resources use librarian curated Subject Guides. To access these resources:

  1. From the Rasmuson Library home page, click Subject Guides.
    " "
  2. Select the subject that best suits your information need.

    For example, if you're looking for background information on the topic of social media, you could select several different subjects, such as Business, Computer Science, Communication, Psychology, or Sociology. For this demonstration, Sociology was selected.
    " "

  3. Click the Background Information tab, and then select a reference resource.

    " "


Other options for finding reference resources:

  • Browse the reference section. The Reference Collection at Rasmuson Library is near the Reference Desk on Level 4. The collection is arranged by Library of Congress (LC) system, starting with general encyclopedias, which can be found on the low shelves, directly behind the Ready Reference Collection. The print indexes fill several shelves on the south end.

  • Ask a Reference Librarian. Ask in-person at the Reference Desk or send your question via email, text, or chat. A librarian will respond to your question via e-mail.

  • Search the Internet. Many university web sites and Internet "virtual libraries" provide access to web reference resources. These subject directories provide access to reliable sources that have already been evaluated according to the criteria of the authors of the site. Or locate reference sources on the Web using a search engine.

    There are good and bad sources available via the Internet. Always evaluate your sources carefully.

    A recommended Google search to look for reference resources is: 

    reference libguides site:edu

    reference libguides site:edu

Works Cited:

Collins, Donald, Diane Catlett, and Bobbie Collins. Libraries and Research: A Practical Approach, 3rd ed. Dubuque. IA: Kendall/Hunt Publishing Company, 1994.

This page was last modified on January 6, 2021