Phainrungruang, Rosaporn, and Peeraphon Lueboonthavatchai. 2014. “Interpersonal Problems and Depression of the Elderly at the Elderly Association in Phitsanulok Province”. Journal of the Psychiatric Association of Thailand 60 (1):23-34. https://he01.tci-thaijo.org/index.php/JPAT/article/view/33406.