Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
hieu van » hieu va, thien van, lieu va
doan van » doan va, hoang van, luan van
va triet » va thiet, va trien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
van bac » van ban, van bao, van hac
va doan » va doanh, van doan, va dan

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 ((nang xa) or (lang xa)) hoi. hieu van bac duc va doan van ((cua triet) OR (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang xa) OR (lang xa)) hoi. hieu van bac duc va doan van ((cua triet) OR (va triet))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((nang xa) or (lang xa)) hoi. hieu van bac duc va doan van ((cua triet) OR (va triet))*".