Bradley, Sarah E.K., William Winfrey, and Trevor N. Croft. 2015. Contraceptive use and perinatal mortality in the DHS: an assessment of the quality and consistency of calendars and histories. DHS Methodological Reports No. 17. Rockville, Maryland, USA: ICF International. Available at http://dhsprogram.com/pubs/pdf/MR17/MR17.pdf.