Perhaps you should try some spelling variations:
cam thue » cam thu, lam thue, nam thue
tai cua » thai cua, tai cuc, tri cua
da nang » cam nang, kha nang, cao nang
va nang » van nang, cam nang, kha nang
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
y nang » ky nang, ly nang, v nang
5 hoi » o hoi

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 y nang ((5 hoi) or (xa hoi)). hieu va cam thue ((va nang) OR (da nang)) tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((5 hoi) OR (xa hoi)). hieu va cam thue ((va nang) OR (da nang)) tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((5 hoi) or (xa hoi)). hieu va cam thue ((va nang) OR (da nang)) tai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((5 hoi) or (xa hoi)). hieu va cam thue ((va nang) OR (da nang)) tai cua tre*.