It is probably important to start out by explaining the difference between a bibliography and a work cited page.  At first glance, both documents seem to be the same and yet they are two very different sorts of assignments. 

A bibliography is a list of all the resources that you are reviewing to find information on your topic or primary source.  You may not end up using all those resources when you go to write your actual research paper, but you had to read through a great deal of scholarly work before you would know what would and would not work in terms of your paper and working towards focusing it around a central issue.

A work cited page, on the other hand, is literally the resources you cited in your actual research paper.  So, even if you read a resource from cover to cover, if you didn't quote, paraphrase, or summarize something from that text in your research paper you cannot list it on your work cited page.  It would be listed in your bibliography, however.