If you have a source with more than one author, the first name listed appears in last name, first name format; the rest of the names appear in first name last name format.
Woodfork, Karen, and Chloe Diamond. "Guide to Wild Catnip Plants." West Virginia Wildflowers. 67.3 (2013): 12-14. ABI / Inform. Web. 7 March 2013.
If there are three or more authors, you can list only the first author followed by the phrase et al. (Latin for "and others"). If you want, you can also list all of the authors in the order in which their names appear.