1. Department of Nursing, Hainan Western Central Hospital, Danzhou, Hainan, China (mainland)
2. Department of Nursing, Cadre Sanatorium of Hainan and Geriatric Hospital of Hainan, Danzhou, Hainan, China (mainland)
3. Department of Cardiology, Chinese People’s Liberation Army Logistic Support Hospital No. 928, Danzhou, Hainan, China (mainland)