Westudythenormretrievalbyprojectionsonaninfinite-dimensionalHilbertspaceH.Let{e_i}_(i∈I)beanorthonormalbasisinHandW_i={e_i}~⊥foralli∈I.Weshowthat{W_i}_(i∈I)doesnormretrievalifandonlyifIisaninfinitesubsetofN.Wealsogivesomepropertiesofnormretrievalbyprojections.