Perhaps you should try some spelling variations:
thien van » thi van
sach doi » sach hoi, sach moi, sach dao
doi nang » dai nang, hoi nang, voi nang
hieu van » hieu va, lieu va, hieu ve
vu sach » vu bach, su sach, vu khach
nang xa » nang x, lang xa, nang ma
hanh di » hanh vi, hanh de, hang di
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach doi nang xa hoi. ((hieu van) or (thien van)) cam ((duc va) or (thuc vat)) hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach doi nang xa hoi. ((hieu van) OR (thien van)) cam ((duc va) OR (thuc vat)) hanh di cua tre.
• Adding a wildcard symbol may retrieve word variants: vu sach doi nang xa hoi. ((hieu van) or (thien van)) cam ((duc va) or (thuc vat)) hanh di cua tre*.