Here are a few articles that I think you may find useful in understanding stuttering and its treatment. It would appear that there is no one theory as to the etiology of stuttering, but these may be helpful.

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Büchel, Christian, and Martin Sommer. "What causes stuttering?." PLoS biology 2.2 (2004): e46.

Craig, A. (2000). The developmental nature and effective treatment of stuttering in children and adolescents. Journal of Developmental and Physical Disabilities, 12(3), 173-186.

Packman, A., Code, C., & Onslow, M. (2007). On the cause of stuttering: Integrating theory with brain and behavioral research. Journal of Neurolinguistics, 20(5), 353-362.

Smith, A. (1990). Factors in the etiology of stuttering. Asha Reports, 18, 39-47.