Reference sources provide foundational knowledge on any topic, and offer relevant names, dates, facts, figures and data. Types of reference sources include dictionaries, encyclopedias, almanacs, and atlases.
Encyclopedias are not acceptable sources to cite in an academic paper, but they are an indispensible start for research that helps you frame your topic. The rich, dynamic content from the online Encyclopædia Britannica combined with Merriam-Webster's Collegiate Dictionary and Thesaurus (both provided by the Massachusetts Libraries), offer reliable sources for students to consult when conducting thorough research.
Think about what kind of information you need; this will help you seek out the best sources for material.
Original materials that provide direct evidence or first-hand testimony concerning a topic or event.
Primary sources can be contemporary sources created at the time when the event occurred (e.g., a novel or poem, letters or diary, newspaper articles) or later (such as, memoirs and oral history interviews).
Primary sources may be published or unpublished. Unpublished sources are unique materials (e.g., family papers) often referred to as archives and manuscripts.
What constitutes a primary source varies by discipline. How the researcher uses the source generally determines whether it is a primary source or not.
Works that interpret, analyze, and discuss the evidence provided by primary sources (e.g., scholarly books and articles).
Secondary sources are generally a second-hand account or observation at least one step removed from the event.
Secondary sources, however, can be considered to be primary sources depending on the context of their use. For example, Ken Burns' documentary of the Civil War is a secondary source for Civil War researchers, but a primary source for those studying documentary filmmaking.
Books or articles that synthesize or distill primary and secondary sources, often in a convenient, easy-to-read form (e.g., dictionaries, encyclopedias, indexes, and textbooks).
Subject encyclopedias are especially useful for getting more specialized background information; for example, this entry, "Animals in Agriculture and Factory Farming," is located in the Encyclopedia of Bioethics. Online reference databases contain hundreds of titles: