Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
van hanh » van thanh, ban hanh, van anh
lang xa » lang ha, dang xay, lang van
hieu va » lieu va, hieu qua
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
du van » duy van, duc van, tu van

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: doc sach _ lang xa hoi. hieu va cac du van hanh di ((cua tre) OR (cuu tre))~.
• Adding a wildcard symbol may retrieve word variants: doc sach _ lang xa hoi. hieu va cac du van hanh di ((cua tre) or (cuu tre))*.