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
va hanh » van hanh, va thanh, va danh
so sach » so sanh, bo sach, co sach
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
ca viet » va viet, co viet, hoa viet
sach v » sach va, sach y, sach 2
luc va » duc va, tuc va, loc va
lai ca » lai cua, lai cam, loai ca

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) OR (tang ma)) hoi. ((hieu vuc) or (hieu luat)) nang luc va hanh lai ca viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach v ((nang ma) OR (tang ma)) hoi. ((hieu vuc) OR (hieu luat)) nang luc va hanh lai ca viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach v ((nang ma) OR (tang ma)) hoi. ((hieu vuc) or (hieu luat)) nang luc va hanh lai ca viet".
• Adding a wildcard symbol may retrieve word variants: so sach v ((nang ma) OR (tang ma)) hoi. ((hieu vuc) or (hieu luat)) nang luc va hanh lai ca viet*.