Perhaps you should try some spelling variations:
thien van » thi van
hieu van » hieu va, lieu va, hieu ve
cam thuc » am thuc, nam thuc, cam thu
hanh dai » hanh tai, hanh dao, vanh dai
sach ky » sach y, sach ty, sach kem
cao hoi » cau hoi, co hoi, cao hoc
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
sac ky » cac ky, sai ky
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) or (sac ky)) nang cao hoi. ((hieu van) or (thien van)) cam thuc va hanh dai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang cao hoi. ((hieu van) OR (thien van)) cam thuc va hanh dai cua te.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang cao hoi. ((hieu van) or (thien van)) cam thuc va hanh dai cua te*.