M. J. Kharodawala and A. K. Rana, “Study on Oximino-3-Methyl-1-(2´ ,4´ -dinitrophenyl)-2-Pyrazolin-5-One as a Gravimetric Reagent for Co(II), Ni(II) and Cu(II) ”, ajc, vol. 14, no. 2, pp. 979–984, Mar. 2010.