1H-Pyrazolo[4,3-d]pyrimidine, 7-amino-3-.beta.-D-ribofuranosyl- 6742-12-7 D-Ribitol, 1-C-(7-amino-1H-pyrazolo[4,3-d]pyrimidin-3-yl)- 1,4-anhydro-, (S)- Formycin A NSC102811