I want to share that before posting a link I (usually) try to check that the store I link to is the best by some objective criterion --- in this case, it's indeed the first Google result. Perhaps this could also be a good thing to put in the FAQ.
]]>Of course, as part of "checks and balances" system, you should check out if you're fine with what I wrote there.
]]>Personally, I'd rather a link to Kepler's bookstore.
]]>My feeling is that linking to Amazon is pretty standard, though my preference is to link to Google books whenever possible.
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