Perhaps you should try some spelling variations:
nhieu viec » nhien viet
hieu viec » hieu ve, sieu viet, hieu hien
cao khoa » lao khoa, bao khoa, cac khoa
hang vi » hang va, hanh vi, hang di
va hang » van hang, va nang, va lang
cac thu » cach thuc, cac thoi
sach ky » sac ky, sach ty, sach kem
cua tre » cua te, cuu tre, cua triet
thu va » thuc va, thue va, tu va
vi cua » vai cua, di cua

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 (sach y)) nang cao khoa. ((hieu viec) or (nhieu viec)) cac thu va hang vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sach y)) nang cao khoa. ((hieu viec) OR (nhieu viec)) cac thu va hang vi cua tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sach y)) nang cao khoa. ((hieu viec) or (nhieu viec)) cac thu va hang vi cua tre*.