Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Marco Caliendo and Sabine Kopeinig,Some Practical Guidance for the Implementation of Propensity Score Matching,SSRN Electronic Journal,1556-5068,Elsevier BV,2005,,,,https://cir.nii.ac.jp/crid/1360579820501340416,https://doi.org/10.2139/ssrn.721907