Perhaps you should try some spelling variations:
hieu quan » lieu quan, thien quan, hieu luat
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
nam tu » nam thu, nam thuc
vi cua » vai cua, di cua
x hoi » xa hoi, o hoi, x ho
lien » bien, vien, tien

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 ky nang x hoi. ((((hieu quan) OR (lien quan))) or (hieu qua)) nam tu va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang x hoi. ((((hieu quan) OR (lien quan))) OR (hieu qua)) nam tu va hanh vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang x hoi. ((((hieu quan) OR (lien quan))) or (hieu qua)) nam tu va hanh vi cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang x hoi. ((((hieu quan) OR (lien quan))) or (hieu qua)) nam tu va hanh vi cua tre*.