Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
va triet » va thiet, va trien, ve triet
dan vai » dan va, dan tai, dan vat
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
ky tang » ky nang, ky dang, kho tang
ky lang » ky nang, ky dang, tay lang
cac tuc » cac toc, cac tu, cac tac
tuc va » thuc va, truc va, tuc xa
va dan » ca dan, va dao, va dau

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

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