Perhaps you should try some spelling variations:
hieu luat » hieu qua
hanh lai » hanh lam, hanh tai, thanh lap
hieu vuc » hieu luc, hieu tuc, hieu thuc
ca viet » va viet, hoa viet, san viet
va hanh » van hanh, va thanh, va danh
so sach » so sanh, bo sach, co sach
co viet » so viet, o viet, hoc viet
nang ma » tang ma, sang ma, nang cao
y nang » ky nang, ly nang, v nang
luc va » duc va, tuc va, loc va
ma hoi » mai hoi, xa hoi, ma hoa

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: so sach y nang ma hoi. ((hieu vuc) OR (hieu luat)) nang luc va hanh lai ((ca viet) OR (co viet))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach y nang ma hoi. ((hieu vuc) or (hieu luat)) nang luc va hanh lai ((ca viet) OR (co viet))~".
• Adding a wildcard symbol may retrieve word variants: so sach y nang ma hoi. ((hieu vuc) or (hieu luat)) nang luc va hanh lai ((ca viet) OR (co viet))*.