The basic principle for citing electronic sources is that the documentation must be sufficient to allow the reader to retrieve the material; if the database is revisable or temporary, like much that appears on the Internet, the documentation must show both when the material was published and when it was accessed.  The documentation guidelines here are from the current MLA Style Manual (2nd ed. 1998) and the MLA Web page http://www.mla.org/ as supplemented by The Mayfield Handbook of Technical & Scientific Writing (1998).

Walker, Janice R. "Columbia Online Style: MLA-Style Citations of
    Electronic Sources." Vers. 1.2, Rev. Nov. 1997. 10. Dec. 1997
    <http://www.cas.usf.edu/english/walker/mla.html>.

For Internet and other revisable online sources, in addition to the information you would provide for a printed source, give the date of publication or the most recent revision, the date of access enclosed in angle brackets (< >). Some authorities recommend, to avoid misreading, not interrupting the URL by a line break and not following it with a period; others say that it is all right to break a URL after a period or a slash if it is too long to fit on one line.

Arnzen, Michael A. "Cyber Citations." Internet World 7.1 (1996):
    30 pars. 15 Oct. 1997 <http://www.internetworld.com/
    1996/09/cybercitations.html>.

To identify the location of a specific passage in an online document, use its paragraph number.  In the citation entry, indicate the number of paragraphs in the entire document.  Add that information after the colon following the date of publication; use the abbreviation "pars." for "paragraphs." 

A document retrieved from a file transfer protocol (FTP) site or a Gopher site is cited in the same way as Web sites, except that the abbreviation ftp or the word gopher (rather than http) precedes the address, which is not enclosed in angle brackets.

APA citations for electronic sources, like those for print sources, have five elements: author, date, title, document type, and publication information.  For the date that appears in parentheses right after the author's name, use the date of the page's most recent revision (if available).  In square brackets after the title of the page, identify the type of page (such as online serial or online database).  For the publciation information, give the date you visited the page and the complete URL (Uniform Resource Locater or the Internet address) enclosed in angle brackets.  (Although the APA does not specify angle brackets, they are an accepted way to avoid confusion about what constitutes the URL.)  If the URL must be broken between two lines, break it after a slash or a period.  Since the fourth education of APA's Publication Manual (1995), APA's style for citing Internet sources has been evolving.  For its online revision of the form to use to cite information from the Internet and the World Wide Web, see <http://www.apa.org/journals/webref.html>.

Central Intelligence Agency. (1998). The World Factbook page on
    Mexico, Section: People. In 1997 World Factbook [Online
    database]. Retrieved November 22, 1998, from the World Wide
    Web: <http://www.odci.gov/cia/publications/factbook/
    country-frame.html>.

For large databases (such as the one in the preceding example), you may not find an author's name on each page; in that case, check the database's home page.

Yoes, C. (1996). The science fiction web project: Adventures in
   teaching with Storyspace [5 paragraphs]. Computers, Writing,
    Rhetoric and Literature 2(1) [Online serial]. Retrieved May 3,
    1997, from the World Wide Web: <http://www.en.utexas.edu/
    ~cwrl/v2n1/yoes/yoes.html>.

A similar format can be used for documents retrieved from file transfer protocol (ftp) and Gopher sites.

[Index] - [Step One] - [Step Two] - [Step Four]