Perhaps you should try some spelling variations:
ve triet » va trien, su triet
tu sach » thu sach, su sach, te sach
hieu ve » hieu va, hieu van
cac tuc » cac toc, cac tu, cac tac
hang vi » hang va, hang di, khang voi
y lang » o lang, tay lang, yen lang
_ lang » o lang, _ land
ve cac » va cac, vien cac
tuc va » thuc va, truc va, tuc xa

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((y lang) OR (_ lang)) xa hoi. hieu ve cac tuc va ((hang vi) OR (hanh vi)) ve triet~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((y lang) OR (_ lang)) xa hoi. hieu ve cac tuc va ((hang vi) or (hanh vi)) ve triet~".
• Adding a wildcard symbol may retrieve word variants: tu sach ((y lang) OR (_ lang)) xa hoi. hieu ve cac tuc va ((hang vi) or (hanh vi)) ve triet*.