Selection rules for inter-and intra-valley scattering processes between the minima of the lowest conduction band G, L, M, and A are investigated in wurtzite ZnO. The knowledge of the selection rules is required for the determination of the ClebschGordon coefficients (CGCs). These coefficients diagonalize the Kronecker products (KPs) of relevant irreducible representations of quasi particles participating in scattering processes. The elements of the scattering tensors are the linear combinations of the CGCs. Within this work, the CGCs for ZnO belonging to the space group C 4 6n are determined.