Author,Title,Journal,ISSN,Publisher,Date,Volume,Number,Page,URL,URL(DOI) Takumi Maeda and Keiichi Kimura and Toshiyuki Shono,Solvent extraction of alkaline earth metal picrates with poly- and bis(crown ether)s,Fresenius' Zeitschrift für analytische Chemie,0016-1152,Springer Science and Business Media LLC,1982-01,313,5,407-410,https://cir.nii.ac.jp/crid/1363670320031054464,https://doi.org/10.1007/bf00495843