Perhaps you should try some spelling variations:
sach thu » sach thue, sach thieu, sach tham
hieu van » hieu va, thien van, lieu va
cam thuc » am thuc, nam thuc, cam thu
danh vai » danh sai, danh va, doanh van
tu sach » thu sach, su sach, te sach
nang xa » nang x, nang ma, mang xa
lang xa » lang ha, dang xay, lang van
van cam » van nam, van lam, van cau
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
vai cua » dai cua, hai cua, lai cua
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 ((nang xa) or (lang xa)) hoi. hieu van cam thuc va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach thu ((nang xa) OR (lang xa)) hoi. hieu van cam thuc va danh vai cua tre.
• Adding a wildcard symbol may retrieve word variants: tu sach thu ((nang xa) or (lang xa)) hoi. hieu van cam thuc va danh vai cua tre*.