World Health Organisation. (1989). Health of the elderly World Health organisation. World Health Organisation.
استشهاد بنمط شيكاغوWorld Health Organisation. Health of the Elderly World Health Organisation. Geneva: World Health Organisation, 1989.
MLA استشهادWorld Health Organisation. Health of the Elderly World Health Organisation. World Health Organisation, 1989.
تحذير: قد لا تكون هذه الاستشهادات دائما دقيقة بنسبة 100%.