Annunziata, M. A., Muzzatti, B., & Altoe, G. (2011). Defining Hospital Anxiety and Depression Scale (HADS) structure by confirmatory factor analysis: a contribution to validation for oncological settings. Annals of Oncology, 22(10), 2330–2333. doi:10.1093/annonc/mdq750 
Barth, J., & Martin, C. R. (2005). Factor structure of the Hospital Anxiety and Depression Scale (HADS) in German coronary heart disease patients. Health and quality of life outcomes, 3(1), 1-9. doi:10.1186/1477-7525-3-15
Bjelland, I., Dahl, A. A., Haug, T. T., & Neckelmann, D. (2002). The validity of the Hospital Anxiety and Depression Scale An updated literature review. Journal of Psychosomatic Research, 52(2), 69-77. doi:10.1016/s0022-3999(01)00296-3 
Bocéréan, C., & Dupret, E. (2014). A validation study of the Hospital Anxiety and Depression Scale (HADS) in a large sample of French employees. BMC Psychiatry, 14(1), 1-11. doi:10.1186/s12888-014-0354-0
Botega , N. J., Pondé , M. P., Medeiros, P., Lima , M. G., & Guerreiro , C. (1998). Validation of the Hospital Anxiety and Depression Scale in ambulatory epileptic patients. Jornal Brasileiro de Psiquiatria, 47(6), 285-289.
Brennan , C., Worrall-Davies , A., McMillan, D., Gilbody , S., & House, A. (2010). The hospital anxiety and depression scale: a diagnostic meta-analysis of case-finding ability. Journal of Psychosomatic Research(69), 371-378. doi:10.1016/j.jpsychores.2010.04.006
Caci, H., Baylé, F. J., Dossios, C., Robert, P., & Boyer, P. (2003). The Spielberger trait anxiety inventory measures more than anxiety. European Psychiatry, 18(8), 394-400. doi: 10.1016/j.eurpsy.2003.05.003 
Cao, W., Fang, Z., Hou, G., Han, M., Xu, X., Dong, J., & Zheng, J. (2020). The psychological impact of the COVID-19 epidemic on college students in China. Psychiatry Research, 287, 112934.
CEPAL, N. U. (2020). América Latina y el Caribe ante la pandemia del COVID-19: efectos económicos y sociales. 
Cosco , T. D., Doyle, F., Ward, M., & McGee, H. (2012). Latent structure of the hospital anxiety and depression scale: a 10-year systematic review. Journal of Psychosomatic Research, 72, 180-184.
Coyne, J. C., & van Sonderen, E. (2012). No further research needed: Abandoning the Hospital and Anxiety Depression Scale (HADS). Journal of Psychosomatic Research, 72(3), 173-174. doi:10.1016/j.jpsychores.2011.12.003
Djukanovic , I., Carlsson , J., & Arestedt , K. (2017). Is the Hospital Anxiety and Depression Scale (HADS) a valid measure in a general population 65–80 years old? A psychometric evaluation study. Health Qual Life Outcomes, 15(1), 193. doi:10.1186/s12955-017-0759-9
Ebel, R. L., & Frisbie, D. A. (1986). Using test and item analysis to evaluate and improve test quality. In Essentials of educational measurement (pp. 223-242). Englewood Cliffs, NJ: Prentice~ Hall.
Emons, W. H., Sijtsma , K., & Pedersen , S. S. (2012). Dimensionality of the Hospital Anxiety and Depression Scale (HADS) in cardiac patients: comparison of Mokken scale analysis and factor analysis. Assessment, 19(3), 337–53. doi:10.1177/1073191110384951
Fornell, C., & Larcker, D. F. (1981). Structural Equation Models with Unobservable Variables and Measurement Error: Algebra and Statistics. Journal of Marketing Research, 18(3), 382–388. doi:10.1177/002224378101800313 
Friedman, S., Samuelian, J. C., Lancrenon, S., Even, C., & Chiarelli, P. (2001). Three-dimensional structure of the Hospital Anxiety and Depression Scale in a large French primary care population suffering from major depression. Psychiatry Research, 104(3), 247–257. doi:10.1016/S0165-1781(01)00309-2
Hinz, A., Finck, C., Gómez, Y., Daig, I., Glaesmer, H., & Singer, S. (2014). Anxiety and depression in the general population in Colombia: reference values of the Hospital Anxiety and Depression Scale (HADS). Social psychiatry and psychiatric epidemiology, 49(1), 41- 49. doi:10.1007/s00127-013-0714-y
Huarcaya-Victoria, J. (2020). Consideraciones sobre la salud mental en la pandemia de COVID-19. Revista Peruana de Medicina Experimental y Salud Pública, 3(7), 1-8. doi:10.17843/rpmesp.2020.372.5419
Iani, L., Lauriola, M., & Costantini, M. A. (2014). Confirmatory bifactor analysis of the hospital anxiety and depression scale in an Italian community sample. Health Qual Life Outcomes, 12(1), 84. doi:10.1186/1477-7525-12-84 
Leung, C. M., Wing, Y. K., Kwong, P. K., & Shum, A. (1999). Validation of the Chinese-Cantonese Validation of the Chinese-Cantonese version of the Hospital Anxiety and Depression Scale and comparison with the Hamilton Rating Scale of Depression. Acta Psychiatrica Scandinavica, 100(6), 456-461. doi:10.1111/j.1600-0447.1999.tb10897.x
Li, C. (2015). Confirmatory factor analysis with ordinal data: Comparing robust maximum likelihood and diagonally weighted least squares. Behavior Research Methods, 48(3), 936–949. doi:doi.org/10.3758/s13428-015-0619-7
Li, W., Yang, Y., Liu, Z. H., Zhao , Y. J., Zhang, L., Cheung, T., & Xiang, Y. (2020). Progression of Mental Health Services during the COVID-19 Outbreak in China. International Journal of Biological Sciences, 16(10), 1732-1738. doi: 10.7150/ijbs.45120
MacCallum, R. C., Widaman, K. F., Preacher, K. J., & Hong, S. (2001). Sample Size in Factor Analysis: The Role of Model Error. Multivariate Behavioral Research, 36(4), 611-637. doi:10.1207/S15327906MBR3604_06
Maters, G. A., Sanderman, R., Kim, A. Y., & Coyne, J. C. (2013). Problems in Cross-Cultural Use of the Hospital Anxiety and Depression Scale: “No Butterflies in the Desert.”. PLoS ONE, 8(8), e70975. doi:10.1371/journal.pone.0070975 
Netemeyer, R. G., Bearden, W. O., & Sharma, S. (2003). Scaling procedures: issues and applications. . Thousand Oaks: Sage.
Norton, S., Cosco, T., Doyle, F., Done, J., & Sacker, A. (2013). The Hospital Anxiety and Depression Scale: A meta confirmatory factor analysis. Journal of Psychosomatic Research, 74(1), 74-81. doi:10.1016/j.jpsychores.2012.10.010 
Olssøn, I., Mykletun, A., & Dahl, A. A. (2005). The Hospital Anxiety and Depression Rating Scale: a cross‐sectional study of psychometrics and case finding abilities in general practice. BMC Psychiatry, 14(5), 46.
Pais Ribeiro, J. L., Martins da Silva, A., Vilhena, E., Moreira, I., Santos, E., & Mendonça, , D. (2018). The hospital anxiety and depression scale, in patients with multiple sclerosis. Neuropsychiatric Disease and Treatment, 14, 3193–3197. doi:10.2147/ndt.s184260 
Rajkumar, R. P. (2020). COVID-19 and mental health: A review of the existing literature. Asian Journal of Psychiatry, 52, 102066. doi:10.1016/j.ajp.2020.102066
Raykov, T. (2001). Estimation of congeneric scale reliability using covariance structure analysis with nonlinear constraints. British Journal of Mathematical and Statistical Psychology, 54, 315-323. doi:10.1348/000711001159582
Razavi, D., Delvaux, N., Farvacque, C., & Robaye, E. (1990). Screening for Adjustment Disorders and Major Depressive Disorders in Cancer In-Patients. The British Journal of Psychiatry, 156(1), 79-83. doi:10.1192/bjp.156.1.79
Saez-Flores , E., Tonarely , N. A., Barker, D. H., & Quittner , A. L. (2018). Examining the stability of the Hospital Anxiety and Depression Scale factor structure in adolescents and young adults with cystic fibrosis: a confirmatory factor analysis. Journal of Pediatric Psychology, 43(6), 625–635. doi:10.1093/jpepsy/jsx155
Straat , J. H., van der Ark , L. A., & Sijtsma , K. (2013). Methodological artifacts in dimensionality assessment of the Hospital Anxiety and Depression Scale (HADS). Journal of Psychosomatic Research, 74(2), 116-121. doi:10.1016/j.jpsychores.2012.11.012
Tejero, A., Guimerá, E. M., Farré , J. M., & Peri, J. M. (1986). Uso clínico del HAD (Hospital Anxiety and Depression Scale) en población psiquiátrica: un estudio de su sensibilidad, fiabilidad y validez. Revista del Departamento de Psiquiatría de la Facultad de Medicina de Barcelona, 13(5), 233-238.
Terol, M. C., López-Roig, S., Rodríguez-Marín, J., Martín-Aragón, M., Pastor, M. A., & Reig, M. T. (2007). Propiedades psicométricas de la Escala Hospitalaria de Ansiedad y Estrés (HAD) en población española. Ansiedad y Estrés, 13(23), 163-176.
Terol-Cantero, M. C., Cabrera-Perona, V., & Aragón, M. (2015). Hospital Anxiety and Depression Scale (HADS) review in Spanish Samples. Anales de Psicología, 31(2), 494-503. doi:10.6018/analesps.31.2.172701
Thorndike, R. M., Cunningham, G. K., Thorndike, R. L., & Hagen, E. P. (1999). Measurement and evaluation in psychology and education (5th ed.). New York: MacMillan.
Villoria, E., & Lara, L. (2018). Assessment of a hospital anxiety and depression scale for cancer patients. Revista medica de Chile, 146, 300-307. doi:10.4067/s0034-98872018000300300
World Health Organization. (2017). Depression and other common mental disorders: Global health estimates. Retrieved from https://www.who.int/mental_health/management/depression/prevalence_global_health_estimates/en/ [Accessed 7 June 2020]
Yamamoto-Furusho, J. K., Sarmiento-Aguilar, A., García-Alanis, M., Gómez-García, L. E., Toledo-Mauriño, J., Olivares-Guzmán, L., & Fresán-Orellana, A. (2018). Escala de Ansiedad y Depresión Hospitalaria (HADS): Validación en pacientes mexicanos con enfermedad inflamatoria intestinal. Gastroenterología y Hepatología, 41(8), 477- 482. doi:10.1016/j.gastrohep.2018.05.009
Yang , Z., Huang, X., Liu , X., Hou , J., Wu , W., Song , A., . . . Wu , H. (2019). Psychometric Properties and Factor Structure of the Chinese Version of the Hospital Anxiety and Depression Scale in People Living With HIV. Frontiers in psychiatry, 346. doi:10.3389/fpsyt.2019.00346
Zandifar, A., & Badrfam, R. (2020). Iranian mental health during the COVID-19 epidemic. Asian Journal of Psychiatry.
Zigmond , A. S., & Snaith, R. P. (1983). The Hospital Anxiety and Depression Scale. Acta Psychiatrica Scandinavica, 67(6), 361-370. doi:http://dx.doi.org/10.1111/j.1600-0447.1983.tb09716.x