Perhaps you should try some spelling variations:
trong huong » trong thuong, trong chuong, truong huong
thieu sach » chieu sach, thien hach, theo sach
trang tuan » tran tuan, trung tuan, tran xuan
trong tuan » trong quan, trung tuan, trong tan
hieu cach » hieu cac, chieu sach, hieu ca
dan toan » van toan, dan than, manh toan
toan cau » toan cao, toan ban, toan tap

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: hoc ((thieu sach) OR (hieu cach)) - hanh ((trang tuan) OR (trong tuan)) trong huong dan toan cau~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc ((thieu sach) or (hieu cach)) - hanh ((trang tuan) OR (trong tuan)) trong huong dan toan cau~".
• Adding a wildcard symbol may retrieve word variants: hoc ((thieu sach) or (hieu cach)) - hanh ((trang tuan) OR (trong tuan)) trong huong dan toan cau*.