Perhaps you should try some spelling variations:
vat thanh » dat thanh, gat thanh, tat thanh
cua triet » cua viet, su triet, va triet
vu khanh » vu thanh, van khanh, duy khanh
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
thanh vi » hanh vi, thanh va, thanh ve
khanh y » khanh ly, hanh y, khanh v
hieu ve » hieu va
cua tre » cua te, cuu tre, dua tren
y nang » ky nang, ly nang, v nang
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu khanh y nang x hoi. ((hieu ve) or (hieu van)) nam thuc vat thanh vi ((cua tre) or (cua triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu khanh y nang x hoi. ((hieu ve) OR (hieu van)) nam thuc vat thanh vi ((cua tre) OR (cua triet)).
• Adding a wildcard symbol may retrieve word variants: vu khanh y nang x hoi. ((hieu ve) or (hieu van)) nam thuc vat thanh vi ((cua tre) or (cua triet))*.