Perhaps you should try some spelling variations:
cam thue » lam thue, nam thue, cam thiet
nang tai » hang tai, tang tai, sang tai
tai cua » thai cua, tai cuc, tri cua
va nang » van nang, da nang, cam nang
cam thu » nam thu, cac thu, ca thu
tu sach » thu sach, su sach, te sach
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
y nang » ky nang, ly nang, v nang
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 5 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 ((x hoi) or (o hoi)). hieu va ((cam thue) OR (cam thu)) va nang tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang ((x hoi) OR (o hoi)). hieu va ((cam thue) OR (cam thu)) va nang tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang ((x hoi) or (o hoi)). hieu va ((cam thue) OR (cam thu)) va nang tai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang ((x hoi) or (o hoi)). hieu va ((cam thue) OR (cam thu)) va nang tai cua tre*.