Always consult with your professor before citing from an abstract–some professors do not allow you to do so. If you do, use the same format as you would for Citing Electronic Resources, only you would add the word Abstract in front of the word retrieved. Thus, a sample citation for a journal article using the APA style would read as follows:
Author, A. A., Author, B. B., and Author, C. C. (Year).
Title of article. Title of Periodical, xx, xxx-xxx.
Abstract retrieved month day, year, from source.
When using the Chicago style, an abstract is treated like a journal article, but the word abstract must be added, thus a sample citation would read as follows:
Author, A. A., Author, B. B., and Author, C. C. "Title of Article."
Abstract. Title of Periodical xx (Year): xxx.