I have had a preliminary look at the following sources. I would be posting my comments about each of these in detail in the next few weeks.

Arthur, J.D., K.T. Stevens. 1989. Assessing the adequacy of documentation through document quality indicators. Software Maintenance, Proceedings., Conference on.

Carliner, Saul. 1997. Demonstrating Effectiveness and Value: A Process for Evaluating Technical Communication Products and Services. Technical Communication. 44(3): 252-65.

Dufty, David, Danielle McNamara, Max Louwerse, Ziqiang Cai, and Arthur Graesser. 2004. Automatic evaluation of aspects of document quality. In Proceedings of the 22nd annual international conference on Design of communication: The engineering of quality documentation (SIGDOC '04). ACM, New York, NY, USA, 14-16.

Hackos, JoAnn. 1994. Managing Your Documentation Projects. New York: John Wiley & Sons.

Hargis, Gretchen. 2000. Readability and computer documentation. ACM Journal of Computer Documentation. 24, 3: 122-131.

Hargis, G., Hernandez, A.; Hughes, P.; Ramaker, J.; Rouiller, S.;Wilde, E. 1998. Developing Quality Technical Information: A Handbook for Writers and Editors. Upper Saddle River, NJ: Prentice- Hall.

Huang, Shihong, and Tilley, Scott. 2003. Towards a documentation maturity model. In Proceedings of the 21st annual international conference on Documentation (SIGDOC '03). ACM, New York, NY, USA, 93-99.

Reilly, Annette. 1993. Professional recognition and respect through quality. Technical Communication. 40(2): 231-33.

Schriver, Karen. 1993. Quality in Document Design: Issues and Controversies. Technical Communication. 40(2): 239-57.

Sheffield, Michael. 1997. Quality Improvement: Benchmarking, Document Design, and the STC. Technical Communication. 44(3): 225-34.

Smart, Karl. 2002. Assessing Quality Documents. ACM Journal of Computer Documentation. 26(3): 130-140.

Smart, Karl, Kristie Seawright, Kristin Bell DeTienne. 1995. Defining Quality in Technical Communication: A Holistic Approach. Technical Communication. 42(3): 474-81.

Smith, Karl. 1996. What is Quality? InterCom. 42-43.

Spilka, Rachel. 2000. The Issue of Quality in Professional Documentation: How Can Academia Make More of a Difference. Technical Communication Quarterly. 9(2): 207-220.