Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
hanh tai » thanh tai, hang tai, han tai
va triet » va thiet, va trien, ve triet
tu sach » thu sach, su sach, te sach
ky lang » ky dang, ky tang, tay lang
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
cac ly » cac ky, cac le, cam ly

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