1. Diwu Z.;He J.;Liao J.Fluorescent ion indicators and their applications to detn. of metal cations. U.S. Pat. Appl. Publ. US 2008254498 2008;
2. Tsien R. Y.;Minta A.Preparation and properties of calcium‐specific long‐wavelength indicator dyes. Eur. Pat. Appl. EP 314480 1989;
3. New calcium indicators and buffers with high selectivity against magnesium and protons: design, synthesis, and properties of prototype structures