Perhaps you should try some spelling variations:
cua triet » su triet, va triet
hanh than » hanh han, hanh nhan, hanh phan
cua viet » ca viet, hoa viet, cua vat
tu sach » thu sach, su sach, te sach
lang xa » lang ha, dang xay, lang van
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, va danh
ve cac » va cac, vien cac

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