Citation: Jl. Abad et al., N-15-multilabeled adenine and guanine nucleosides. Syntheses of [1,3,NH2-N-15(3)]- and [2-C-13-1,3,NH2-N-15(3)]-labeled adenosine, guanosine, 2 '-deoxyadenosine, and 2 '-deoxyguanosine, J ORG CHEM, 64(18), 1999, pp. 6575-6582