著者名,書名,版表示,出版者名,出版年,シリーズ名,番号,ISBN,ISSN,URL "Olomola, Ade",Choice and productivity effects of animal traction technology in the semi-arid zone of Northern Nigeria,,"African Rural Social Sciences Research Networks, Winrock International",1998,Issues in African rural development monograph series,,1573600180,,https://cir.nii.ac.jp/crid/1130282273005432320