Perhaps you should try some spelling variations:
hieu luat » hieu qua
hieu vuc » hieu luc, hieu tuc, hieu thuc
hanh lai » hanh lam, hanh tai, thanh lap
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
va hanh » van hanh, va thanh, va danh
va viet » hoa viet, san viet, mai viet
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
ma hoi » mai hoi, xa hoi, ma hoa
luc va » duc va, tuc va, loc va
lai va » loai va, mai va, dai va

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach v nang ma hoi. ((hieu vuc) or (hieu luat)) nang luc va hanh lai va viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v nang ma hoi. ((hieu vuc) OR (hieu luat)) nang luc va hanh lai va viet.
• Adding a wildcard symbol may retrieve word variants: so sach v nang ma hoi. ((hieu vuc) or (hieu luat)) nang luc va hanh lai va viet*.