Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
va triet » va thiet, va trien, ve triet
dang xay » dang van, van xay
khai tuc » thai tuc, khai thac, khai tuan
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
lang xa » lang ha, lang van
va khai » van khai, va khao, va kha
tuc va » thuc va, truc va, tuc xa

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