1. [1] American Psychiatric Association. Diagnostic and statistical manual of mental disorders, 5th Edition: DSM5. Washington, DC, USA: American Psychiatric Association; 2013. [DOI:10.1176/appi.books.9780890425596]

2. [2] Centers for Disease Control and Prevention (CDC). Prevalence of autism spectrum disorder among children aged 8 years - autism and developmental disabilities monitoring network, 11 Sites, United States, 2014. MMWR Surveill Summ 2018; 67: 1-23. [DOI:10.15585/mmwr.ss6706a1] [PMID] [PMCID]

3. [3] Kerns CM, Kendall PC, Berry L, Souders MC, Franklin ME, Schultz RT, et al. Traditional and atypical presentations of anxiety in Youth with Autism spectrum disorder. J Autism Dev Disord 2014; 44: 2851-2861. [DOI:10.1007/s10803-014-2141-7] [PMID] [PMCID]

4. [4] Wijnhoven LA, Creemers DH, Vermulst AA, Granic I. Prevalence and risk factors of anxiety in a clinical Dutch sample of children with an autism spectrum disorder. Front Psychiatry 2018; 9: 50. [DOI:10.3389/fpsyt.2018.00050] [PMID] [PMCID]

5. [5] Behzadpoor S, Pouretemad H, Akbari Zradkhaneh S. Caregiver-rated anxiety symptoms in an Irainian sapmple of preschoolers with ASD: prevalence and predictors. Iran J Psychiatry 2020. (Persian). [DOI:10.1101/2020.10.22.20217711]

6. [6] Canitano R. Self injurious behavior in autism: clinical aspects and treatment with risperidone. J Neural Transm 2006; 113: 425-431. [DOI:10.1007/s00702-005-0337-x] [PMID]

7. [7] Cervantes P, Matson JL, Tureck K, Adams HL. The relationship of comorbid anxiety symptom severity and challenging behaviors in infants and toddlers with autism spectrum disorder. Res Autism Spectr Disord 2013; 7: 1528-1534. [DOI:10.1016/j.rasd.2013.09.005]

8. [8] Vasa RA, Kalb L, Mazurek M, Kanne S, Freedman B, Keefer A, et al. Age-related differences in the prevalence and correlates of anxiety in youth with autism spectrum disorders. Res Autism Spectr Disord 2013; 7: 1358-1369. [DOI:10.1016/j.rasd.2013.07.005]

9. [9] Adams D, Clark M, Simpson K. The relationship between child anxiety and the quality of life of children, and parents of children, on the autism spectrum. J Autism Dev Disord 2019; 25: 1-4. [DOI:10.1007/s10803-019-03932-2] [PMID]

10. [10] Hallett V, Lecavalier L, Sukhodolsky DG, Cipriano N, Aman MG, McCracken JT, et al. Exploring the manifestations of anxiety in children with Autism spectrum disorders. J Autism Dev Disord 2013; 43: 2341-2352. [DOI:10.1007/s10803-013-1775-1] [PMID] [PMCID]

11. [11] Spence SH, Rapee R, McDonald C, Ingram M. The structure of anxiety symptoms among preschoolers. Behav Res Ther 2001; 39: 1293-12316. [DOI:10.1016/S0005-7967(00)00098-X]

12. [12] Franz L, Angold A, Copeland W, Costello EJ, Towe-Goodman N, Egger H. Preschool anxiety disorders in pediatric primary care: Prevalence and comorbidity. J Am Acad Child Adolesc Psychiatry 2013; 52: 1294-1303. [DOI:10.1016/j.jaac.2013.09.008] [PMID] [PMCID]

13. [13] Keen D, Adams D, Simpson K, den Houting J, Roberts J. Anxiety-related symptomatology in young children on the autism spectrum. Autism 2019; 23: 350-358. [DOI:10.1177/1362361317734692] [PMID]

14. [14] Van Steensel FJ, Bögels SM, Perrin S. Anxiety disorders in children and adolescents with autistic spectrum disorders: a meta-analysis. Clin Child Fam Psychol Rev 2011; 14: 302. [DOI:10.1007/s10567-011-0097-0] [PMID] [PMCID]

15. [15] Gadow KD, DeVincent CJ, Pomeroy J, Azizian A. Psychiatric symptoms in preschool children with PDD and clinic and comparison samples. J Autism Dev Disord 2004; 34: 379-393. [DOI:10.1023/B:JADD.0000037415.21458.93] [PMID]

16. [16] Hollocks MJ, Pickles A, Howlin P, Simonoff E. Dual cognitive and biological correlates of anxiety in autism spectrum disorders. J Autism Dev Disord 2016; 46: 3295-3307. [DOI:10.1007/s10803-016-2878-2] [PMID]

17. [17] Vasa RA, Mazurek MO. An update on anxiety in youth with autism spectrum disorders. Curr Opin Psychiatry 2015; 28: 83. [DOI:10.1097/YCO.0000000000000133] [PMID] [PMCID]

18. [18] Eussen ML, Van Gool AR, Verheij F, De Nijs PF, Verhulst FC, Greaves-Lord K. The association of quality of social relations, symptom severity and intelligence with anxiety in children with autism spectrum disorders. Autism 2013; 17: 723-735. [DOI:10.1177/1362361312453882] [PMID]

19. [19] Kerns CM, Winder-Patel B, Iosif AM, Nordahl CW, Heath B, Solomon M, Amaral DG. Clinically significant anxiety in children with autism spectrum disorder and varied intellectual functioning. J Clin Child Adolesc Psychol 2020; 23: 1-6. [DOI:10.1080/15374416.2019.1703712] [PMID]

20. [20] Mazurek MO, Kanne SM. Friendship and internalizing symptoms among children and adolescents with ASD. J Autism Dev Disord 2010; 40: 1512-1520. [DOI:10.1007/s10803-010-1014-y] [PMID]

21. [21] Snow AV, Lecavalier L. Comparing Autism, PDD-NOS, and other developmental disabilities on parent-reported behavior problems: little evidence for ASD subtype validity. J Autism Dev Disord 2011; 41: 302-310. [DOI:10.1007/s10803-010-1054-3] [PMID]

22. [22] Rosenberg RE, Kaufmann WE, Law JK, Law PA. Parent report of community psychiatric comorbid diagnoses in autism spectrum disorders. Autism Res Treat 2011; 20: 1-10. https://doi.org/10.1155/2011/874619 [DOI:10.1155/2011/405849] [PMID] [PMCID]

23. [23] Sukhodolsky DG, Scahill L, Gadow KD, Arnold LE, Aman MG, McDougle CJ, et al. Parent-Rated anxiety symptoms in children with pervasive developmental disorders: frequency and association with core autism symptoms and cognitive functioning. J Abnorm Child Psychol 2008; 36: 117-128. [DOI:10.1007/s10802-007-9165-9] [PMID]

24. [24] Mayes SD, Calhoun SL, Murray MJ, Zahid J. Variables associated with anxiety and depression in children with autism. J Dev Phys Disabil 2011; 23: 325-337. [DOI:10.1007/s10882-011-9231-7]

25. [25] Black KR, Stevenson RA, Segers M, Ncube BL, Sun SZ, Philipp-Muller A, et al. Linking anxiety and insistence on sameness in autistic children: The role of sensory hypersensitivity. J Autism Dev Disord 2017; 47: 2459-2470. [DOI:10.1007/s10803-017-3161-x] [PMID]

26. [26] Kalvin CB, Marsh CL, Ibrahim K, Gladstone TR, Woodward D, Grantz H, et al. Discrepancies between parent and child ratings of anxiety in children with autism spectrum disorder. Autism Res 2020; 13: 93-103. [DOI:10.1002/aur.2220] [PMID] [PMCID]

27. [27] Gall MD, Borg WR, Gall JP. Educational research: An introduction. Longman Publishing; 2013.

28. [28] Delavar A. Research methods in psychology and educational sciences. Virayesh publishing; 2018

29. [29] Ahmadi S, Safari T, Hemmatian M, Khalili Z. The psychometric properties of gilliam autism rating scale (G5ARS). Res Cogn Behav Sci 2011; 1: 87-104. (Persian).

30. [30] Poushneh K, Siam N, Abedi M. The effectiveness of reciprocal imitation training on reducing symptoms of children with autism disorder. Psychol Except Individ 2014; 4: 1-19. (Persian).

31. [31] Edwards SL, Rapee RM, Kennedy SJ, Spence SH. The assessment of anxiety symptoms in preschool-aged children: The revised preschool anxiety scale. J Clin Child Adolesc Psychol 2010; 39: 400-409. [DOI:10.1080/15374411003691701] [PMID]

32. [32] Ghanbari S, Khanmohamadi M, Khodapanahi MK, Mazaheri MA, Gholamali LM. Study of psychometric properties of preschool anxiety scale (PAS). J Psychol 2011; 15: 222-234. (Persian).

33. [33] Scahill L, Challa SA. Repetitive behavior in children with autism spectrum disorder: Similarities and differences with obsessive-compulsive disorder. In: Mazzone L, Vitiello B, editors. psychiatric symptoms and comorbidities in autism spectrum disorder. Cham: Springer International Publishing; 2016; 39-50. [DOI:10.1007/978-3-319-29695-1_3]

34. [34] Van Ameringen M, Patterson B, Simpson W. DSM-5 obsessive-compulsive and related disorders: Clinical implications of new criteria. Vol. 31, Depression and Anxiety. Depress Anxiety 2014; 31: 487-493. [DOI:10.1002/da.22259] [PMID]

35. [35] MacLennan K, Roach L, Tavassoli T. The relationship between sensory reactivity differences and anxiety subtypes in autistic children. Autism Res 2020; 13: 785-795. [DOI:10.1002/aur.2259] [PMID]

36. [36] Potter LA, Scholze DA, Biag HM, Schneider A, Chen Y, Nguyen DV, et al. A randomized controlled trial of sertraline in young children with autism spectrum disorder. Front Psychiatry 2019; 10: 810-826. [DOI:10.3389/fpsyt.2019.00810] [PMID] [PMCID]

37. [37] Salazar F, Baird G, Chandler S, Tseng E, O'sullivan T, Howlin P, et al. Co-occurring psychiatric disorders in preschool and elementary school-aged children with autism spectrum disorder. J Autism Dev Disord 2015; 45: 2283-2294. [DOI:10.1007/s10803-015-2361-5] [PMID]

38. [38] Behzadpoor S, Pouretemad HR, Akbari Zradkhaneh S. Risk factors of anxiety in children and adolescents with autism spectrum disorder: a systematic review. J Child Ment Heal 2020; Under Public (Persian).

39. [39] Pearson DA, Loveland KA, Lachar D, Lane DM, Reddoch SL, Mansour R, et al. A comparison of behavioral and emotional functioning in children and adolescents with autistic disorder and PDD-NOS. Child Neuropsychol 2006; 12: 321-333. [DOI:10.1080/09297040600646847] [PMID]

40. [40] Hofmann SG, Moscovitch DA, Heinrichs N. Evolutionary mechanisms of fear and anxiety. In: Gilbert P, editor. Evolutionary Theory and Cognitive Therapy. New York, NY, US: Springer Publishing; 2004; 119-136.

41. [41] Sadock BJ, Sadock VA, Ruiz P. Kaplan & Sadock's comprehensive textbook of psychiatry. Philadelphia, PA: Lippincott Williams & Wilkins; 2017; 127.

42. [42] Bernstein GA, Layne AE, Egan EA, Nelson LP. Maternal phobic anxiety and child anxiety. J Anxiety Disord 2005; 19: 658-672. [DOI:10.1016/j.janxdis.2004.09.001] [PMID]

43. [43] Williams S, Leader G, Mannion A, Chen J. An investigation of anxiety in children and adolescents with autism spectrum disorder. Res Autism Spectr Disord 2015; 10: 30-40. [DOI:10.1016/j.rasd.2014.10.017]

44. [44] Magiati I, Ong C, Lim XY, Tan JW-L, Ong AY, Patrycia F, et al. Anxiety symptoms in young people with autism spectrum disorder attending special schools: Associations with gender, adaptive functioning and autism symptomatology. Autism 2016; 20: 306-320. [DOI:10.1177/1362361315577519] [PMID]

45. [45] Behzadpoor S, Pouretemad HR, Akbari Zradkhaneh S. Developmental Skills required for the effectiveness of Cognitive Behavior Therapies in children: An umbrella review. Clin Excell 2019; 9: 46-55. (Persian).