Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Osamu Kamada,Theoretical concentration and attainable temperature in solar furnaces,Solar Energy,0038-092X,Elsevier BV,1965-01,9,1,39-47,https://cir.nii.ac.jp/crid/1360294674816672000,https://doi.org/10.1016/0038-092x(65)90159-3