Ukoha, P. O.; Ekere, N. R.; Opara, I. J. STUDIES ON EXTRACTION OF Co (II) IONS FROM AQUEOUS SOLUTION USING 1,5-DIMETHYL- 2- PHENYL-4-[(E)-(2,3,4-TRIHYDROXYLPHENYL)DIAZENYL]-1,2-DIHYDRO-3H-PYRAZOL-3-ONE. JCSN 2017, 40.