Perhaps you should try some spelling variations:
hieu cac » hieu va, hieu van, vien cac
hanh lai » hanh lam, hanh tai, thanh lap
hieu luc » hieu luat, hieu qua
lai cua » dai cua, hai cua, lai chau
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, tu cach
nang xa » nang x, lang xa, nang ma
te sach » toc sach
cua te » cua tu
bo va » bao va, do va, so va

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) or (te sach)) ky nang xa hoi. hieu ((hieu cac) OR (hieu luc)) bo va hanh lai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) ky nang xa hoi. hieu ((hieu cac) OR (hieu luc)) bo va hanh lai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (te sach)) ky nang xa hoi. hieu ((hieu cac) OR (hieu luc)) bo va hanh lai cua te".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (te sach)) ky nang xa hoi. hieu ((hieu cac) OR (hieu luc)) bo va hanh lai cua te*.