Is this new, or has GBS always sometimes done this? I’ve never seen it refuse to show me the excerpts on a page that matched my query before.
Page 197
Historians say, In the pre-Islamic era [in Arabia] (al-Jahiliyyah) there were four persons from Quraysh, each one of whom owned one …Page 327
Sorry, this page’s content is restricted.Page 328
Sorry, this page’s content is restricted.
Actually, I think I’m pretty sure it’s not true. I have noted before that some GBS books with “limited preview” actually offer upwards of 95% of the book, only leaving out a handful of pages. I guess I never did a search before that had hits on one of those handfull of pages.
Still very odd, wonder how they decide what pages to leave out.
Bibliographic Wilderness 
There is a discussion in the API documentation that passing the original IP address determines what content they can see.