Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hanh tai » thanh tai, hang tai, han tai
nam thuc » nam thuoc, am thuc, nam thu
hieu van » hieu va, thien van, lieu va
hang ca » hang va, nang cao, hang tai
sach ly » sach y, sach lo, sach ty
hang xa » hoang xa, hang va, lang xa
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
cua tre » cua te, cuu tre, cua triet
so sach » so sanh, bo sach, co sach

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

• Performing a fuzzy search may retrieve terms with similar spellings: so sach ly ((hang xa) or (hang ca)) hoi. hieu van nam thuc va hanh tai ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ly ((hang xa) OR (hang ca)) hoi. hieu van nam thuc va hanh tai ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: so sach ly ((hang xa) or (hang ca)) hoi. hieu van nam thuc va hanh tai ((cua tre) or (cau tren))*.