I just found a bit more about the Green paper...

Sitnacs sent it to Earth without realizing it could help us. To them it was useless, but to a human Prophecy-maker, priceless. As it was a papery substance, had been in contact with a Sitnac General, it was used to predict what was going too happen (I think it's how S.A knew to send this stuff, as she uncovered more).The predictions written on it, plus sticking it back together would have been enough to stop the Sitnacs. But it was too late...

To make a point to the rodent union, the hamsters destroyed three of the pieces (they didn't know the significance, just that the mice wanted them).

All might be lost...