Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
va hanh » van hanh, va thanh, va danh
cac thu » cach thuc, cac thoi
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
van cac » van hac, van cau, van bac
thu va » thuc va, thue va, tu va

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 y ((nang xa) or (nang ma)) hoi. hieu van cac thu va hanh vi ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach y ((nang xa) OR (nang ma)) hoi. hieu van cac thu va hanh vi ((cua tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: so sach y ((nang xa) or (nang ma)) hoi. hieu van cac thu va hanh vi ((cua tre) or (cau tren))*.