An online source may appear as an abstract, an excerpt, or a full-text work. It is important to distinguish among these versions of sources and to use a complete version of a source, preferably one with page numbers, for your research.

Abstracts and excerpts are shortened versions of complete works. An abstract—a summary of a work’s contents—might appear in a database record for a source and can give you clues about the usefulness of the source for your paper. Abstracts are brief (usually fewer than five hundred words) and often do not contain enough information to function alone as sources in a research paper. Reading the complete article is the best way to understand the author’s argument before referring to it in your own writing. If you cannot access the complete article electronically, ask a librarian if the library has a print copy.

An excerpt is the first few sentences or paragraphs of a newspaper or magazine article and sometimes appears in a list of hits in an online search. From an excerpt, you can often determine whether the complete article would be useful for your paper. Be sure to retrieve and read the full text of any article you might want to cite.

A full-text work may appear online as a PDF file or as an HTML file (sometimes called a text file). A PDF file is usually an exact copy of the pages of an article or a book as they appeared in print, including the page numbers. A full-text document that appears as an HTML or a text file is not paginated. If your source is available in both formats, choose the PDF file for your research because you will be able to cite specific page numbers.