Perhaps you should try some spelling variations:
sach thu » sach thue, sach tham, cach thuc
hieu van » hieu va, thien van, lieu va
ban hanh » ban hang
nang xa » nang x, lang xa, nang ma
van bao » van ban, van dao
bao duc » dao duc, bao luc, cao duc
va hanh » van hanh, va thanh, va danh
cuc tre » duc tre, cua tre, cuu tre

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 thu) OR (sach thieu)) nang xa hoi. hieu van bao duc ((va hanh) or (ban hanh)) tai cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu ((sach thu) OR (sach thieu)) nang xa hoi. hieu van bao duc ((va hanh) OR (ban hanh)) tai cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu ((sach thu) OR (sach thieu)) nang xa hoi. hieu van bao duc ((va hanh) or (ban hanh)) tai cuc tre".
• Adding a wildcard symbol may retrieve word variants: vu ((sach thu) OR (sach thieu)) nang xa hoi. hieu van bao duc ((va hanh) or (ban hanh)) tai cuc tre*.