On the left-hand side go under the Literature heading and scroll down to Critical Insights-Themes.  Critical insights Hero's Quest and under Critical Surveys-  Critical Survey of Mythology and Folklore: World Mythology. may help with your project.

Go under the History heading and open Ancient World.  Search for Mythology. 

Another option. use the general search box in Salem Press to search for Mythology or a specific type of mythology such as Celtic Mythology..

For poetry, do a general search in the database.