[LisaS]

If that's a serious question and not rhetorical, then I'd say that the publisher who supplied the books to the seller had full knowledge of how they'd be displayed and gave consent to that browsing pre-sale use. As would a publisher who sold books to libraries. I think the case could be made that those uses are to be considered differently than scanning & posting online in a public forum.

In a similar manner, Amazon has made some "look inside" arrangements with publishers for some works and Google books is excerpting pages from books via arrangement with the publisher. But you probably know more about copyright than I do.

Whether the concepts make sense in a digital world I don't know. If the book is published I'll respect the rights notice in the text. That's an ethical decision for me to abide by the rights notice.

As far as rights and information content goes, then conventional citation norms should be followed for citing a source. And this outside of plagerism considerations for schemes or methods (I'm thinking of the bruhaha(s) earlier on this and other forums over some fitness information and marketing texts). But none of those were happening here - just a scan of a page that was properly credited to the source.