Ionization Constants Relationship

K_a₁, K_a₂ and K_a₃ are respective ionization constants for the following reactions (a), (b) and (c).
(a) H₂C₂O₄ ⇌ H⁺ + HC₂O₄⁻
(b) HC₂O₄⁻ ⇌ H⁺ + C₂O₄²⁻
(c) H₂C₂O₄ ⇌ 2H⁺ + C₂O₄²⁻
The relationship between K_a₁, K_a₂ and K_a₃ is given as