CMMC offers cover-to-cover (“core”) indexing and abstracts for more than 550 journals, and selected (“priority”) coverage of nearly 200 more, for a combined coverage of 737 titles. Furthermore, this database includes full text for over 440 journals.
Dates of coverage: Some journals have full text available back to their first issue (as early as 1915)
Full text? PARTIAL.
You will want to build the bulk of your bibliography from communication databases. However, if you are exploring a topic that touches on other issues (women's studies, organizations, etc), you may wish to see if there are useful articles to you in other subject databases. A few suggestions are below:
Going backward in time? Look at the bibliography/reference list of the article. In communication and Mass Media, some of the articles have a separate link for the "Cited References."
Going forward in time? Look to see who has cited your article. Communication & Mass Media sometimes has "Cited By" links, but Google Scholar is much more comprehensive in identifying citations of your article.