Strong 0 1s and Cu 2p resonant enhancements are observed in the valence-band photoemission spectra of BizSr2CaCu20&, CuO, and Cu20. The results can be accounted for by a model Hamiltonian with similar parameters but different band filling. The 0 ls (Cu 2p) resonant enhancements are found to be dominated by local 0 2p4 (Cu 3d8) final states reached via local intra-atomic processes; interatomic 0-to-Cu resonance processes are found to play only a minor role. It is demonstrated that enhancements observed at 0-1.5 eV binding energies in angle-resolved photoemission of Bi2Sr2Ca-Cu20& with the photon energy tuned at 18 eV cannot be attributed to an 0 2s resonance effect.

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