Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
dang cay » dang ca, dang cac, dung cay
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
hanh dai » hanh tai, hanh dao, vanh dai
nam tuc » nam thuc, nam truc, nam tu
xa hanh » xa thanh, xa khanh, va hanh
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: tu ((sach thu) or (sach y)) ((dang cay) OR (dang xay)) phoi. hieu van nam tuc xa hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach thu) OR (sach y)) ((dang cay) OR (dang xay)) phoi. hieu van nam tuc xa hanh dai cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach thu) or (sach y)) ((dang cay) OR (dang xay)) phoi. hieu van nam tuc xa hanh dai cua tre*".