Neilson Hays library, near British Club on Surawong road. Heritage building with garden. Website: http://www.neilsonhayslibrary.com/
For other libraries in Bangkok, see here:
10 libraries to seek peace and quiet in Bangkok
(Library in Goethe Institute Sathorn is missing, you can read German language newspaper for free.)
Neilson Hays library has a book sale every year in May and November, the next is Sat-Sun 15.-16.11, 9:30-16:00.
Last year it was Sat-Sun 15.-16.11.2013, I was there and took the following pictures and left with the following prey:
(Prices are color coded with a label.)
I have read one of them, started another and used the map. That (having more unread than read books from last year) will not prevent me from going this and year and buying more.
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