Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hanh dai » hanh tai, hanh dao, vanh dai
tru nang » tra nang, tri nang, truc nano
truc va » thuc va, thuc vat, trung va
te sach » toc sach
hieu va » lieu va, hieu qua
tu nang » tu nong, tu nano, tu lang
tuc va » thuc va, tuc xa, duc va
dai va » mai va
va cao » va cac, va co, va dao

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

• Performing a fuzzy search may retrieve terms with similar spellings: te sach ((tu nang) or (tru nang)) xa hoi. hieu va cao ((tuc va) OR (truc va)) hanh dai va triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: te sach ((tu nang) OR (tru nang)) xa hoi. hieu va cao ((tuc va) OR (truc va)) hanh dai va triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach ((tu nang) or (tru nang)) xa hoi. hieu va cao ((tuc va) OR (truc va)) hanh dai va triet".
• Adding a wildcard symbol may retrieve word variants: te sach ((tu nang) or (tru nang)) xa hoi. hieu va cao ((tuc va) OR (truc va)) hanh dai va triet*.