[talamown]

Amazon already has been doing this as well.

They started to recommend some items related with books I have never bought online, just after I got them at local bookstore by credit card.

[Graphon1]

Isn't there a difference? Google is sharing that offline purchase insight with advertising clients, rather than simply using that data itself, as does Amazon.

[lern_too_spel]

Where the advertising client is the local bookstore that he purchased the book from.