Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
vung tay » vung tau, dung tai, vung dat
tan vanh » tan van, tan vinh, tan thanh
vanh dai » van dai, vanh tai, lanh dao
dan tay » ban tay, dao tay, gian tay
hieu va » hieu qua
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach y ((vung tay) or (dan tay)) hoi. ((hieu va) OR (lieu va)) giao duc tan vanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y ((vung tay) OR (dan tay)) hoi. ((hieu va) OR (lieu va)) giao duc tan vanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y ((vung tay) or (dan tay)) hoi. ((hieu va) OR (lieu va)) giao duc tan vanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach y ((vung tay) or (dan tay)) hoi. ((hieu va) OR (lieu va)) giao duc tan vanh dai cua tre*.