Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hanh dai » hanh tai, hanh dao, vanh dai
va hanh » van hanh, va thanh, va danh
nang xa » nang x, lang xa, nang ma
sach va » sach xa, sach ha, sach dao
cua tre » cua te, cuu tre, cua triet
sach v » sach y, sach 2, sach vay

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 v) or (sach va)) nang xa hoi. hieu van ((nhan luc) OR (nang luc)) va hanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach v) OR (sach va)) nang xa hoi. hieu van ((nhan luc) OR (nang luc)) va hanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach v) or (sach va)) nang xa hoi. hieu van ((nhan luc) OR (nang luc)) va hanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach v) or (sach va)) nang xa hoi. hieu van ((nhan luc) OR (nang luc)) va hanh dai cua tre*.