1. Shafiei B, Rezaei- rad A. Cluttering. Isfahan: Isfahan University of Medical Sciences; 2003:10-29. [Persian]
2. Watkins K, Smith S, Davis S, Howell P. Structural and functional abnormalities of the motor system in developmental stuttering Brain. 2008; 131(1): 50-9.
3. Azimi T, Pooladi SH, Mahmoodi Bakhtiari B, Haghani H. Effects of the Utterance Length on Fluency of Conversational Speech in Stuttering Persian-Speaker Children and Adults. Rehabilitation Journal 2013; 14(3): 41-46. [Persian]
4. Howell P, Au- Yeung J, Sackin S. Internal structure of content words leading to lifespan differences in phonological difficulty in stuttering. Journal of Fluency Disorders 2000; 5: 1-20.
5. Howell P, Au-Yeung J. The EXPLAN theory of fluency control applied to the diagnosis of stuttering. In: Fava, E., editor. Clinical Linguistics: Language Pathology, Speech Therapy, and Linguistic Theory Amsterdam Studies in the Theory and History of Linguistic Science Series 4 2002; 227: 75-94.
6. Howell P. Assessment of some contemporary theories of stuttering that apply to spontaneous speech. Sci Disord 2004; 31(Contemp Issues Commun): 122–39.
7. Smith A, Sadagopan N, Walsh B, Weber-Fox C. Increasing phonological complexity reveals heightened instability in inter-articulatory coordination in adults who stutter. Journal of Fluency Disorders. 2010; 35(1): 1-18.
8. Bajaj A. Working memory involvement in stuttering: exploring the evidence and research implication. Journal of Fluency Disorders 2007; 32: 218-238.
9. Baddeley AD. Working memory and language: an overview. Journal of Communication Disorders 2003; 36: 189-208.
10. Wingate ME. Stuttering and word length. Journal of Speech and Hearing Research 1967; 10: 146-152.
11. Eriksen CW, Pollack MD, Montague WE. Implicit speech: Mechanism in perceptual encoding. Journal of Experimental Psychology1970; 84(3):502-507.
12. Danzger M, Halpern H. Relation of stuttering to word abstraction part of speech, word length, and word frequency. Perceptual and Motor Skills 1973; 37(3): 959-962.
13. Byrda T, Anderson M, Sussman H. NNonword repetition and phoneme elision in adult who do and donot tutter. Journal of Fluency Disorder 2012; 37(3): 188-201.
14. Ludlow C, Siren K, Zirkria M. Speech production learning in adult with chronic developmental stuttering. Journal of Speech Production: Motor Control, Brain Research and Fluency Disorders 1997: 221-230.
15. Riecker A, Brendel B, Ziegler W, Erb M, Ackermann H. The influence of syllable onset complexity and syllable frequency on speech motor control. Brain and Language 2008; 107:102–113.
16. Howell P, Au-Yeung J, Yaruss S. Phonetic difficulty and stuttering in English. Clin Linguist Phon 2006; 20(9): 703-716.
17. Dayalu VN, Kalinowski J, Stuart A. Stuttering frequency on meaningful and non-meaningful words in adults who stutter. Folia Phoniatr Logop 2005; 57: 193-201.
18. Guitar B. Stuttering: an integrated approach to its nature and treatment.3rd ed. Philadelphia, PA: Lippincott Wilkiam & Wilkins; 2006:185-195.
19. Masumi E, Arani Kashani Z, Ghorbani A, Kamail M. A study of effect word/ non-word length and syllable structure on frequency of non- fluency in adult with developmental stuttering [Thesis], Rehabilitation Faculty, Iran University of Medical Sciences, 2013:58-102.[Persian]
20. Farazi M, Tehrani L, Khodabakhshi A, Shemshadi H, Ranjbar M. Compile cognitive and speech approach protocol and determine its effectivence in treating of the adult Persian speaker who stuttering (PWS) [thesis], University of Welfare and Rehabilitation Sciences, 2011. [Persian]
21. Weber- Fox C, Spencer R, Spruill J, Smith A. Phonologic orocessing in adult who stutter: Electrophysiological and behavioral evidence. Journal of speech, Language, and Hearing Research 2004; 34: 311- 334.
22. Au-Yeung J, Howell P. Non-word reading, lexical retrieval and stuttering: Comments onPackman, Onslow, Coombes and Goodwin (2001). Clinical Linguistics& Phonetics 2002; 16(4): 287–293.
23. Brocklehurst P. A review evidence for the covert repair hypothesis of stuttering. Sci Disord 2008; 35(Contemp Issues Commun): 25-43.
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