Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
hanh tai » thanh tai, hang tai, han tai
hanh dai » hanh dao, vanh dai, thanh dat
tru nang » tra nang, tri nang, truc nano
cao tuc » dao tuc, cao duc, cao suc
te sach » toc sach
hieu va » lieu va, hieu qua
tu nang » tu nong, tu nano, tu lang
tuc va » thuc va, truc va, tuc xa
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 ((hanh dai) OR (hanh tai)) 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 ((hanh dai) OR (hanh tai)) 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 ((hanh dai) OR (hanh tai)) va triet".
• Adding a wildcard symbol may retrieve word variants: te sach ((tu nang) or (tru nang)) xa hoi. hieu va cao tuc va ((hanh dai) OR (hanh tai)) va triet*.