1. C-nucleosides: aspects of chemistry and mode of action
2. Chapter 9 of reference 1a.
3. For example, formycin is readily converted to the less active formycin B (i.e., 3-(β-D-ribofuranosyl) pyrazolo[4,3-d]py-rimidin-7(6H) one) by adenosine deaminase and this is believed (2) to account for the development of organism resistance to formycin.