Perhaps you should try some spelling variations:
thuat sach » thuat lanh, thuat san
hanh tai » thanh tai, hang tai, han tai
van hanh » van thanh, ban hanh, van anh
tai cua » thai cua, tai cuc, tri cua
kham ly » khao ly, khanh ly
hieu so » thieu so
sach ty » sach y, sach tu, sach thu
hieu vu » hieu va, hieu ve, hieu su
tang ma » mang may, tang van
nang ma » sang ma, nang cao, mang may
cua tre » cua te, cuu tre, cua triet
ly van » le van, ly va, ly von

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

• Performing a fuzzy search may retrieve terms with similar spellings: thuat sach ty ((nang ma) OR (tang ma)) hoi. ((hieu vu) or (hieu so)) kham ly van hanh tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thuat sach ty ((nang ma) OR (tang ma)) hoi. ((hieu vu) OR (hieu so)) kham ly van hanh tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thuat sach ty ((nang ma) OR (tang ma)) hoi. ((hieu vu) or (hieu so)) kham ly van hanh tai cua tre".
• Adding a wildcard symbol may retrieve word variants: thuat sach ty ((nang ma) OR (tang ma)) hoi. ((hieu vu) or (hieu so)) kham ly van hanh tai cua tre*.