Olson, K., Lepkowski, J.M. and Garabrant, D.H. (2011) “An Experimental Examination of the Content of Persuasion Letters on Nonresponse Rates and Survey Estimates in a Nonresponse Follow-Up Study”, Survey Research Methods, 5(1), pp. 21–26. doi:10.18148/srm/2011.v5i1.4324.