Skicka posten per e-post: Guanidinium (aqua-2κO)(4-hydr­oxy-6-carboxy­pyridine-2-carboxyl­ato-2κ(3) O (2),N,O (6))(μ-4-hydroxy­pyridine-2,6-dicarboxyl­ato-1:2κ(4) O (2),N,O (6):O (2))(4-hydroxy­pyridine-2,6-dicarboxyl­ato-1κ(3) O (2),N,O (6))dizincate(II) dihydrate