1. World population prospects: the 2010 revision;United Nations,2011
2. The 2011 World Population Data Sheet;Bureau,2011
3. Population aging in sub-Saharan Africa: demographic dimensions 2006: US Dept. of Commerce, Economics and Statistics Administration, US Census Bureau;Velkoff,2007
4. World youth report. Young people's transition to adulthood: progress and challenges;United Nations,2007
5. Limits to modern contraceptive use among young women in developing countries: a systematic review of qualitative research;Williamson;Reproductive Health.,2009