Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hanh dai » hanh tai, hanh dao, vanh dai
hieu va » lieu va
va hanh » van hanh, va thanh, va danh
dai cuu » dai cua, dai huu
cuu tre » cua tre, cau tren, cau treo
xang x » nang x

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) ty xang x ho. ((hieu va) OR (hieu qua)) cac nuoc va hanh dai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ty xang x ho. ((hieu va) OR (hieu qua)) cac nuoc va hanh dai cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ty xang x ho. ((hieu va) OR (hieu qua)) cac nuoc va hanh dai cuu tre*".