Perhaps you should try some spelling variations:
cua tre » cua te, cua triet, dua tren
hac tuc » thac toc, thai tuc
cuu tre » cau tren, cau treo
danh vi » hanh vi, dinh vi, danh di
va danh » va dinh, va dan, va hanh
hieu va » lieu va, hieu qua
tuc va » thuc va, truc va, tuc xa
tu sac » tu sach, tu cac, tu san
va hac » van hac, va khac, va cac
sac ky » cac ky, sai ky
o hoi » co hoi, o hoc, o hai
x hoi » xa hoi, x ho, 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: tu sac ky nang ((x hoi) or (o hoi)). hieu va hac tuc va danh vi ((cuu tre) OR (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sac ky nang ((x hoi) OR (o hoi)). hieu va hac tuc va danh vi ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sac ky nang ((x hoi) or (o hoi)). hieu va hac tuc va danh vi ((cuu tre) OR (cua tre))".
• Adding a wildcard symbol may retrieve word variants: tu sac ky nang ((x hoi) or (o hoi)). hieu va hac tuc va danh vi ((cuu tre) OR (cua tre))*.