Why are these particular google books unsafe?

In the attached picture, there are a few google book rated unsafe by web rep module. But searching http://books.google.com.hk/, avast says its safe. So why are these particular flagged as unsafe?

The 9 search results are
htxp://books.google.com.hk/books?isbn=1478609222
htxp://books.google.com.hk/books?isbn=0080442978
htxp://books.google.com.hk/books?id=ff88AAAAIAAJ
htxp://books.google.com.hk/books?isbn=148326632X
htxp://books.google.com.hk/books?isbn=0470335467
htxp://books.google.com.hk/books?isbn=1606238310
htxp://books.google.com.hk/books?isbn=1593856415
htxp://books.google.com.hk/books?isbn=0080858996
htxp://books.google.com.hk/books?isbn=0080537030

Edit: May be this is a bug in the avast web rep module? I see it marked safe when I clicked into one of this.
But on the search result page, it is still marked as unsafe.
Just in case this is real bug and is search key related, I was searching information about a website blocked by avast. The website is htxp://ma.ws341.com/05/main.js?t=0.1610672793579253, and I search “ma.ws341. com” .

Hi rickyyeung,

The place to look for where that flagging came for is of course the IP: 64.233.182.100
And to consider the whole badness history of that site and what malcode was being launched from that IP:
https://www.virustotal.com/en/ip-address/64.233.182.100/information/
For instance I see a ParetoLogic, which makes me frown as they are known to be running after the facts and detections therefore may be questionable.
What has been detected from there? Avast found: Win32:Dropper-gen [Drp], so-called fake-App aka Android:FakeInst-RT [Trj],
HTML:Phishing-Q [Trj], Banker malware aka Win32:Malware-gen,

I think it could be narrowed to these alerts found here: http://urlquery.net/report.php?id=1413682614508
see Files Captured from 62.213.66.66
exfile.ru/download/467124 exfile dot ru
MD5 6abe39d77e17111e613a8f1386ad87f6 → https://www.virustotal.com/en/file/5f22b22794f7f3998b25c387d0ef8c943fe412e5efe886ea221bd3b1197a5b65/analysis/1413634262/

However this threat has not been detected by avast yet?

polonus