Perhaps you should try some spelling variations:
thu sach » tu sach, thuat sach, thuoc sach
hanh dai » hanh tai, hanh dao, vanh dai
te sach » toc sach
hieu su » hieu sau, hieu so, hieu suat
tieu su » thieu so
ngoc va » nuoc va, ngoc ha, goc va
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) or (te sach)) ky nang x hoi. ((hieu su) OR (tieu su)) pham ngoc va hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (te sach)) ky nang x hoi. ((hieu su) OR (tieu su)) pham ngoc va hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (te sach)) ky nang x hoi. ((hieu su) OR (tieu su)) pham ngoc va hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (te sach)) ky nang x hoi. ((hieu su) OR (tieu su)) pham ngoc va hanh dai cua tre*.