Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
duc van » duc va, duc tan, duc manh
luc van » luoc van, luu van, luc va
cua tre » cua te, cuu tre, cua triet
ve cac » va cac, vien cac
vi cua » vai cua, di cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((tu sach) or (thu hoach)) ky nang cao hoi. hieu ve cac ((duc van) or (luc van)) hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu hoach)) ky nang cao hoi. hieu ve cac ((duc van) OR (luc van)) hanh vi cua tre.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (thu hoach)) ky nang cao hoi. hieu ve cac ((duc van) or (luc van)) hanh vi cua tre*.