One-electron Hartree-Fock operator

As a result of the mean-field approximation, those pairs of Slater determinants that differ by more than one spin-orbital no longer contribute. This approximation is based on an idea similar to the conversion of the ordinary full electronic Hamiltonian into the one-electron Hartree-Fock operator and can be interpreted as describing electronic motion in an averaged field of the other electrons. 

Prove that the one-electron Hartree-Fock operator (13.149) is Hermitian. 

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