( “Topological LC-circuits based on microstrips and observation of electromagnetic modes with orbital angular momentum” Yuan Li, Yong Sun, Weiwei Zhu, Zhiwei Guo, Jun Jiang,
Toshikaze Kariyado, Hong Chen and Xiao Hu; journal : Nature Communications, 9, 4598 (2018) DOI:
10.1038/s41467-018-07084-2)