I take it you mean you are deployed on active service in the military. What is the nature of the course you are taking? Is it an Internet distance learning course? Or is it a military course offered through your branch of the service?
If it is a long distance course, such courses usually have academic research programs purchased that the student can access online. There are several and each gives you access to a good number of online databases through your course login. For example, you might login to the various databases with your University student number and password. One example of such databases is JSTOR online research database. I can't say with authority, but I would guess a military sponsored educational program would have the same sort of thing. You would contact your course representative for details.
In lieu of this option, an alternative is to do a Google search--although Bing is often better for academic search results--for the topic and/or authors' or critics' names you may have come across in your readings. I've presonally found much good information on esoteric linguistic topics in this fashion, so I would guess Oedipus Rex would also have much information available. Google Scholar is devoted to scholarly sources, but the results generally are to sources that require a course sponsored login as discussed above.
Here are a few I found on Bing for you by using the whole search term phrase Oedipus Rex Aristotle tragic hero+edu (+edu filters for only academic sources):
Outline of Aristotle's Theory of Tragedy in the POETICS
Oedipus as the Ideal Tragic Hero
Critics names from a Wikipedia reference list
Bremer, J.M.; Dawe, R D.; Hyde, Isabel; Moles, J. L.; Stinton, T. C. W.; Golden, Leon,
Aristotle on Greek Tragedy; by Dr. Larry A. Brown, Professor of Theater
This is a DOC: a Word Document:
www.nyu.edu/classes/reichert/cf/c1/Dodds_Oedipus.txt.doc · Cached page · DOC file
List of relevant ebooks and articles
Oedipus the Cliché: Aristotle on Tragic Form and Content
Christopher S. Morrissey, Department of Humanities, Simon Fraser University
Oedipus: The Definition of a Tragic Hero. Krantz
Oedipus the Wreck; Professor Eric Hibbison, J. Sargeant Reynolds Community College
Well, the best place to start is by doing your own research in whatever library you have access too and maybe asking for help from a librarian to find suitable texts that might contain the information that you need. Also, if you are studying this text as part of your college work, your teacher should be a good starting point to provide some initial ideas of important works of criticism that he can refer you to. These should help you gain an idea of the main critical perspectives that there are out there. Often I find that when I start researching a topic like this the books I read will point me towards other books expressing opposite or similar ideas. Every work of criticism should summarise the works of others that have gone before it, identifying whether the author agrees or disagrees with the other ideas and also, crucially, talking about how the author intends to build on those ideas and how.
So my biggest piece of advice is to start reading from the resources that you have already been given and pay careful attention to references made to other texts, that should help you find a wider range of criticism to use in your research. Good luck!
The first best place to look for resources is Entoes itself. Within the Oedipus Rex Study Guide is a page called "Essays and Criticism" (link provided below) with contributions by three scholars on the play. These all involve a discussion of the play as a classic Tragedy, so you should find some helpful information on Oedipus as a Tragic Hero there.
You should also count your work with the original material, both the play Oedipus Rex itself and Aristotle's Poetics, as source material. A link is also provided below to Enotes page on the Poetics. Make sure to provide quotes from this text that make direct reference to Aristotle's definition of a Tragic Hero, as this term has been used and re-used since the time of the Greek theatre and has come to mean different things depending upon whose definition you refer to.
And finally, I have provdided a link to the Enotes Study Guide on Oedipus Rex's "Bibliography and Further Reading" page, which gives other potential sources of material. Good luck!
You should always just read the play and analyze it. An author writes a play for a reader to interpret it the way they want. For example, you may think everything in Oedipus happened because he was fated to do so, or it was because he was too eager to know the truth.