Perhaps you should try some spelling variations:
cua triet » cua viet, su triet
va triet » va thiet, va trien, ve triet
hanh tai » thanh tai, hang tai, han tai
qua cham » qua hai, qua cac, va cham
va hanh » van hanh, va thanh, va danh
vu sach » vu bach, su sach, vu khach
sach ty » sach y, sach tu, sach thu
cham su » cham soc, cham cuu, achat su
su va » su van, tu va

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach ty ((nang cao) or (nang x)) hoi. hieu qua cham su va hanh tai ((cua triet) OR (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ty ((nang cao) OR (nang x)) hoi. hieu qua cham su va hanh tai ((cua triet) OR (va triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ty ((nang cao) or (nang x)) hoi. hieu qua cham su va hanh tai ((cua triet) OR (va triet))".
• Adding a wildcard symbol may retrieve word variants: vu sach ty ((nang cao) or (nang x)) hoi. hieu qua cham su va hanh tai ((cua triet) OR (va triet))*.