Natthapon Veerachalee, Pongpol Taweema, and Apisit Songsasen, “Complexation and Spectrophotometric Determination of Cobalt(II) Ion with 3-(2′-thiazolylazo)-2,6-diaminopyridine”, Agr. Nat. Resour., vol. 41, no. 4, pp. 675–680, Dec. 2007.