Perhaps you should try some spelling variations:
sach thue » sach thieu, sach tham, cach thuc
sach thu » sach thieu, sach tham, cach thuc
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
van cam » van nam, van lam, van cau
thuc va » thuc vat, thuc dan, thuc day
dan vai » dan va, dan tai, dan vat
vai cua » dai cua, hai cua, lai cua
cua tre » cua te, cuu tre, cua triet
va dan » ca dan, va dao, va dau
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 thu) or (sach thue)) nang x hoi. hieu van cam thuc va dan vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach thu) OR (sach thue)) nang x hoi. hieu van cam thuc va dan vai cua tre.
• Adding a wildcard symbol may retrieve word variants: thu ((sach thu) or (sach thue)) nang x hoi. hieu van cam thuc va dan vai cua tre*.