1. Online: https://www.jstage.jst.go.jp/article/kagakukyouiku/20/3/20_KJ00003480087/_pdf
2. Nd, Dy cost, online: http://mric.jogmec.go.jp/wp-content/old_uploads/reports/resources-report/2011-08/MRv41n2-06.pdf#search=%27Dy+Nd+%E5%80%A4%E6%AE%B5%27
3. Y. Kikuchi, M. Matsumiya, and S. Kawakami, Solv. Extr. Res. Dev. Jpn. 21, 137. (2014).
4. H. Murakami, H. Sasaki, T. Yasuda, H. Yamamoto, A. Takashima, and T. Kohzuma, Chem. Lett. 44, 1028. (2015).
5. M. Moore, A. Gebert, M. Stoica, M. Uhlemann, and W. Loser, J. Alloys Compd. 647, 997. (2015).