Hi Sokheang Thea,

One book on Speaking for the IELTS test that you may find useful is the book written by me and it is available at Angkor Bookshop, Street 130 near Central Market, opposite side of the stree to Online office, near Norodom Boulevard. It costs 1.80USD and covers all aspects of the Speaking tests as well as some useful tips and practice exercises.
It is 'IELTS SPEAKING AND WRITING IDEAS' by Paul Brown (MA CELTA)
www.5steps2english.com book and published by Angkor bookshop.

Hope that helps,

Paul