Linked from
The 8 pages that link to Guanosine, each with the reason it gives.
Guanosine monophosphateCompared with: Removing GMP's phosphate yields guanosine.
CytidineCompared with: It shares cytidine’s ribose but has a different purine base.
RibavirinCompared with: Ribavirin resembles guanosine but has a distinct triazole carboxamide base.
UridineCompared with: It contrasts with uridine in both base family and base identity.
InosineCompared with: It is another RNA purine nucleoside, with a different base from inosine.