On Apr 12, 9:31 am, "John R. Yamamoto-Wilson"
wrote:
Pereira de Lisboa wrote:
Can I safely place these books along with other books? Or must
I isolate them to avoid the issue spreading?

There are several processes that result in something that people
generally call foxing. Some of it is probably chemical (and will not
normally spread), but quite often it is fungal (and will spread given
the right conditions).

Since he said the books weren't that old, it would seem that the cause
is more likely fungal than chemical. Just my $.02