Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Tsunoi Masayuki,Estimation of the opportunity costs of land clearing/breaking in the antebellum North,經濟學論叢,03873021,The Doshisha Economic Association,2010-03-20,61,4,811-848,https://cir.nii.ac.jp/crid/1390009224913615744,https://doi.org/10.14988/pa.2017.0000012516