Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) SAGE Polio Working Group,Proposed policy for a global switch from 'tOPV to bOPV' for routine immunization,http://www.who.int/immunization/sage/meetings/2012/april/2_Polio_WG_background_paper_26_Mar2012.pdf,,,2012,,,,https://cir.nii.ac.jp/crid/1570291224353293184,