Logic9 (Sudoku pocket books)

Dear Mr. Tan,
A few years ago, NTUC printed Logic9, which is the same as Sudoku. I like the size of Logic9 which is small to fit into the pocket. It is very useful when I am in a plane or train. I looked for it in a few bookstores, but it is not available. Where can I buy it?

REPLY
NTUC Income stopped selling the Logic9 (Sudoku) books two years ago. They do not have the stock any more. I have some stock of Vol 2 to 4. I have placed them for sale at my website at a 20% discount for 3 volumes). You can click on "details" to see a photo of the books.

The stock is limited and will run out soon. If you are interested, you should place your order now. It is useful as a gift.