I used all of the following literature to write my Bachelor thesis about usability testing. Contact me at hello[at]janahrend.com if you’d like to borrow some of the books (and I know you personally).
The list is sorted alphabetically according to the author’s name.

Beyond the Usability Lab: Conducting Large-Scale User Experience Studies.
Alber, William; Tullis, Thomas; Tedesco, Donna: Morgan Kaufmann, Burlington 2010.

Usability of Complex Information Systems: Evaluation of User Interaction.
Albers, Michal J.; Still, Brian: CRC Press, Boca Raton 2011.

Usability Testing Essentials: Ready, Set…Test!
Barnum, Carol: Morgan Kaufmann, Burlington 2011.

Evaluating User Experience in Games: Concepts and Methods.
Bernhaupt, Regina: Springer-Verlag, London 2010. 

Design For How People Learn.
Dirksen, Julie: New Riders, Berkeley 2012.

Moderating Usability Tests: Principles & Practices for Interacting.
Dumas, Joe; Loring, Beth: Morgan Kaufmann, Burlington 2008.

A Practical Guide to Usability Testing.
Dumas, Joseph; Redish, Janice: Intellect Books, Exeter 1999.

Effective Software Testing: 50 Specific Ways to Improve Your Testing.
Dustin, Elfriede: Addison-Wesley, Boston 2003.

Verification, Validation and Testing of Engineered Systems.
Engel, Avner: Wiley, Hoboken 2010.

Designing The Obvious: A Common Sense Approach to Web & Mobile Application Design.
Hoekman, Robert: 2nd Edition, New Riders, Berkeley 2011.

Journal of Usability Studies (2011) Vol. 6 Issue 4
Keselman, Alla; Cid, Victor; Perry, Matthew; Steinberg, Claude; Wood, Fred. B; Siegel, Elliot R.: Adapting Web 1.0 Evaluation Techniques for E-Government in Second Life.

Journal of Usability Studies (2007) Vol. 2 Issue 3
Redish, Janice: Expanding Usability Testing to Evaluate Complex Systems.

Don’t Make Me Think: A Common Sense Approach to Web Usability.
Krug, Steve: 2nd Edition, New Riders, Berkeley 2000.

Rocket Surgery Made Easy.
Krug, Steve: New Riders, Berkeley 2010.

Rocket Surgery Made Easy.
Krug, Steve: Addison-Wesley, München 2010.

Observing the User Experience.
Kuniavsky, Mike: Morgan Kaufmann, San Francisco 2003.

User Interface Design: A Software Engineering Perspective.
Lauesen, Soren: Pearson Education, Harlow 2005.

Usability Testing and System Evaluation: A Guide for Designing Useful Computer Systems.
Lindgaard, Gitte: Chapman & Hall, London 1994.

End-to-End Game Development: Creating Independent Serious Games and Simulations from Start to Finish.
Iuppa, Nick; Borst, Terry: Focal Press, Burlington 2010.

New Trends on Human-Computer Interaction: Research, Development, New Tools and Methods.
Macías, José; Granollers, Toni: Springer-Verlag, London 2009.

Evaluating User Experience in Games: Concepts and Methods.
Bernhaupt, Regina: Springer-Verlag, London 2010.

Using the RITE method to improve products; a definition and a case study.
Medlock, Michael C.; Wixon, Dennis; Terrano, Mark; Romero, Ramon L.; Fulton, Bill: Usability Professional Association, Orlando 2002.

Usability Engineering.
Nielsen, Jakob: Academic Press, London 1993.

Game Usability: Advancing the Player Experience.
Isbister, Katherine; Schaffer, Noah: Morgan Kaufmann, Burlington 2008.

Usability Testing for Library Websites: A Hands-On Guide.
Norlin, Elaina; Winter, CM!: American Library, Chigago 2002.

Usability Engineering: Scenario-Based Development of Human-Computer Interaction.
Rosson, Mary Beth; Carroll, John Millar: Morgan Kaufmann, San Francisco 2002.

Interaction Design: Beyond Human-Computer Interaction.
Rogers, Yvonne; Sharp, Helen; Preece, Jenny: 3rd Edition, Wiley, Indianapolis 2011.

Handbook of Usability Testing – How to Plan, Design, and Conduct Effective Tests.
Rubin, Jeffrey; Chisnell, Dana: 2nd Edition, Wiley, Indianapolis 2008.

Human-Centered Software Engineering: Integrating Usability in the Software Development Lifecycle.
Seffah, Ahmed; Gulliksen, Jan: 8th Edition, Springer-Verlag, Dordrecht 2005.

The Human-Computer Interaction Handbook: Fundamentals, Evolving Technologies and Emerging Applications.
Sears, Andrew; Jacko, Julie: 2nd Edition, Lawrence Erlbaum, New York Abingdon 2008.

Usability Evaluation And Interface Design: Cognitive Engineering, Intelligent Agents And Virtual Reality.
Smith, Michael James; Salvendy, Gavriel: Lawrence Erlbaum, Mahwah 2001.

User Interface Design and Evaluation.
Stone, Debbie; Jarrett, Caroline: Morgan Kaufmann, San Francisco 2005.

Measuring the User Experience: Collecting, Analyzing, and Presenting Usability Metrics.
Tullis, Tom; Albert, Bill: Morgan Kaufmann, Burlington 2008.

Noddy’s Guide to Usability Testing and Gaming.
Weedon, Ben: In: Interfaces (2006) Issue 69, S. 19-21.

Human Computer Interaction Research in Web Design And Evaluation.
Zaphiris, Panayitoits; Kurniawan, Sri: Idea Group, Hershey 2007.