Pfaffian formulas for non equivalent bases

Pfaffian formulas used to compute overlaps necessary to carry out generator coordinate method calculations using a set of Hartree- Fock- Bogoliubov wave functions, is generalized to the case where each of the HFB states are expanded in different arbitrary bases spanning different sub-space of the Hilbert space. The formula obtained is compared with previous results proving to be completely equivalent to them. A discussion of equivalent formulas obtained in the literature is carried out.