khayat,P . (2008). The study of elderly health care services in the world. Social Security Journal, 9(4), 99-144.

khayat,P . "The study of elderly health care services in the world", Social Security Journal, 9, 4, 2008, 99-144.

khayat P. (2008). 'The study of elderly health care services in the world', Social Security Journal, 9(4), pp. 99-144.

P khayat, "The study of elderly health care services in the world," Social Security Journal, 9 4 (2008): 99-144,

khayat P. The study of elderly health care services in the world. Social Security Journal. 2008;9(4):99-144 (In Persian).