Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam tu
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
hanh le » thanh le, hanh ve, hanh de
cua tre » cua te, cuu tre, cua triet
te sac » te sach, te cac, te san
sac ky » cac ky, sai ky
le cua » ly cua
x hoi » xa hoi, o hoi, 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: te sac ky nang ((x hoi) OR (x ho)). hieu van ((nam thuc) or (nam thu)) ban hanh le cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sac ky nang ((x hoi) OR (x ho)). hieu van ((nam thuc) OR (nam thu)) ban hanh le cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sac ky nang ((x hoi) OR (x ho)). hieu van ((nam thuc) or (nam thu)) ban hanh le cua tre".
• Adding a wildcard symbol may retrieve word variants: te sac ky nang ((x hoi) OR (x ho)). hieu van ((nam thuc) or (nam thu)) ban hanh le cua tre*.