1. Global Polio Eradication Initiative. Polio: data and monitoring. 2015. Geneva, Switzerland: Global Eradication Initiative; 2015. http://www.polioeradication.org/Dataandmonitoring/Poliothisweek.aspx.
2. Update on vaccine-derived polioviruses—worldwide, January 2014–March 2015.;Diop;MMWR Morb Mortal Wkly Rep,2015
3. Global Polio Eradication Initiative. Reporting and classification of vaccine-derived polioviruses: GPEI guidelines. Geneva, Switzerland: Global Eradication Initiative; 2015. http://www.polioeradication.org/Portals/0/Document/Resources/VDPV_ReportingClassification.pdf.
4. Global Polio Eradication Initiative. Polio eradication strategy: routine immunization. Geneva, Switzerland: Global Eradication Initiative; 2015. http://www.polioeradication.org/Aboutus/Strategy/Routineimmunization.aspx.
5. Introduction of inactivated poliovirus vaccine and switch from trivalent to bivalent oral poliovirus vaccine—worldwide, 2013–2016.;Immunization Systems Management Group of the Global Polio Eradication Initiative;MMWR Morb Mortal Wkly Rep,2015